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Dual Current Integrator with Servo Control Option User Manual

1. HV Module JPR 2 setting JPR 4 setting 1000 V fe e NEG ee VE 2 POS 3 500 V o o NEG 1 o o HVE O O POS 3 4200 V rL 1 IM o HVE al e POS 3 1000 V E 1 1 2 Q HVE NEG v POS so 500 V 9 9 i m neo f SS POS 3 5 200 V POS 3 1200 User Manual 1200_UM_110905 Page 72 of 119 PSI System Controls and Diagnostics 17 Connectors 17 1 Front panel connectors 17 1 1 Auxiliary I O Nine pin Dsub female Pin 5 Pin 1 Pin 9 Pin 6 External view on connector solder side of mating plug 1 Analog Gnd 6 Analog output Process control DAC 2 Analog Gnd 7 Analog input 3 24 VDC out 8 PSU Gnd 24 V rtn 4 Opto common 9 Opto in B 5 Opto in A 17 1 2 Signal inputs Coaxial BNC socket two channel 1 and channel 2 To mate with a standard BNC plug Core signal Outer screen shield at chassis GND Triaxial female connectors are available as an option two channel 1 and channel 2 To mate with three lug standard triaxial connector such as Trompeter PL74 7 To adapt to BNC use adaptor Trompeter ADBJ20 E2 PL75 Core signal at chassis ground Outer screen shield Inner screen shield at GND at analog ground Two lug triaxial connectors are available to special order as a further option 17 1 3 Auxilia
2. Sw2 Sw2 e i se 1 Integrating on Cy 2 Collecting on C Ch P Cy Sw1 m Swi L 0 i o P IC i E Cs V E WV Sw2 Sw2 id o w oo Ch 4 Collecting on C Ch ee ER Sw1 i s o a 2 a 8 i C 2 Sw2 Sw ea Ww or 5 Transfer charge O5 6 Integrating on on Ce s from C to Cj bs ae Swi o 4 ERES 0 ES C Z Z Figure 32 Switching sequence for the no lost charge method 1200 User Manual 1200_UM_110905 Page 56 of 119 PSI System Controls and Diagnostics Consider the integrator working normally with charge accumulating on Cs and thus voltage increasing at the output 1 The mode 2 no charge loss reset cycle starts by opening the input switch Sw1 2 If the load parallel resistance is high the only place that the source current can now go is to build up charge on C The integrator is now reset 3 by closing Sw1 charge continues to accumulate on C 4 When Sw1 closes again the accumulated charge transfers quickly to Cs This is because the effective input capacitance of the integrator is much greater that C due to the amplifier action 5 The integrator output voltage jumps upward as a result of the transferred charge Assuming lossless transfer the net result is to extend the integration time over the complete reset cycle so that all of the incoming charge is measured The integration now proceeds normally again 6 i t Sw1
3. PSI System Controls and Diagnostics 3 Safety Information This unit is designed for compliance with harmonized electrical safety standard EN61010 1 2000 It must be used in accordance with its specifications and operating instructions Operators of the unit are expected to be qualified personnel who are aware of electrical safety issues The customer s Responsible Body as defined in the standard must ensure that operators are provided with the appropriate equipment and training The unit is designed to make measurements in Measurement Category I as defined in the standard CAUTION The 200 can generate high voltages as follows t or 1000 V DC at 1mA maximum Present on the central conductor of the SHV connector These voltages and currents are not classified as hazardous live under EN61010 but may nevertheless give a noticeable shock The user must therefore exercise appropriate caution when using the device and when connecting cables Power should be turned off before making any connections In applications where high energy charged particle beams can strike electrodes which are normally connected to the I200 voltages limited only by electrical breakdown can build up if the I200 is not connected to provide the earth return path The user must ensure that a suitable earth return path is always present when the particle beam may be present The unit must not be operated unless correctly assembled in its case Protection f
4. GATE IN amm bs FIBER OPTIC 66 1mm 888mm t _ 111 6 mm 39 1345mm N 1495m Figure 1 1200 chassis end panels Dimensions mm 1200 User Manual 1200 UM 110905 Page 19 of 119 PSI System Controls and Diagnostics 4x 3 57 mm MOUNTING HOLE 2X 2X 167 7 mm 164 4 mm 144 0 mm 161 3 mm ww v P x 2X 152 0 mm Z 4 54 mm 161 1 mm 4 170 3 mm Ecc 140 8 mm Figure 2 1200 case side and plan views above Dimensions mm 1200 User Manual 1200 UM 110905 Page 20 of 119 PSI System Controls and Diagnostics 9 How the I200 Works an Overview The 1200 is a very flexible instrument which uses a charge measurement method that may be unfamiliar to you This section gives you an overview of how incoming signal current is turned into readings and the main features of the device Full details are in the later sections of this manual Signal b In A gt gt Signal InB Charge to voltage conversion lt p gt Comms Processor Servo control S1 option Gate input trigger Figure 3 1200 simplified block diagram The 1200 has a two signal input channels which convert very small currents to measureable voltages The voltages are measured
5. eere eere eere teret tatnen tata e tatnen stata ete ta sns ta ene se tato ese tn ense tasa sns tasa en 102 22 1 DCM STaDilzllOfi testes reor dee ptt die e te eter e tae e seres tea e t eet 102 22 2 Process parameter OpllOng eese RE HERE e o e i ied tn Re mee teres 104 1200 User Manual 1200 UM 110905 Page 5 of 119 PSI System Controls and Diagnostics 24 25 26 27 28 29 30 22 3 Process parameter normalization Al sid en et ier t n a m Ple de ae a these 105 22 4 Servo algorithm teo ttp bn E UNO nen 105 22 5 Servo Ting i ne ee b e e as A eh au 106 The LOOAB Option P 109 ELS E HU To 111 Maintenance MARS T 114 Returns ProCeQuire AD M 115 LN aS 11I n Oe EE 116 IBIG TESE I E E EAEI EERE ES 117 Declaration of Conformity 4 eee eee e eee sees eene eene etes te tense tn setas tensa stas etas etas ss tses senes ease ease eass iossss 118 Revision FIStOLY dc 119 1200 User Manual 1200 UM 110905 Page 6 of 119 PSI System Controls and Diagnostics 2 Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 9 Schematic 1200 installation Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18
6. dicen 78 18 4 7 MIENNE EE 79 18 4 8 EK e H 79 19 Communications Interfaces eee eerie eese eene tnt on stata tns tn tns tnsta enata stans ossia eas tn sensns ens en eae iiei 80 20 Communications protocols e eeee esee eene eese ee eere eene tn seen setas taste stes tn sets seta setas es seas e ease ense ta seas eae sense eaae 82 20 1 Di JaurA ES 82 20 2 ASCH Protocol S PL ato au eot a UI NEG ed DN qu a DEER 63 20 2 1 M SSAgeS en ote oq ede daten iei eot Rodin 83 20 2 2 Stats LESISCELS p 83 20 2 3 Host Commands 5 deo Red up NU e ERE eeu 85 20 3 ASCH Protocol Terminal Mode eee ee eee eee sehen enne eth e tnn tn tete tee tete tnn testen etes ennt 95 20 4 Binary protocol aep TREO TR RU DTE EG NEP ERR e E beg d ues 95 21 Techniques for Making Low Current Measurements eerie esee entes esent s tenens tasas tasto senses sesenta 96 21 1 Guarding and sCFeenIng ss i d wen tt tie a tte etatis 96 21 2 Acum 98 21 3 Triboelectric effects i e Ue ted Ep EDU D GARE SC eee 98 21 4 Battery EPP OK T 98 21 5 Piezoelectric Effects e dere a e b eet pg oti es 99 21 6 Integration Period and Synchronization eese teen een eene nennen rennen 99 21 7 SUMMAI xu eH e RR RUTRUM et beta ave qiu nea 100 22 Servo Control Applications
7. addr of last device TERMinal 011 Set query terminal mode password protected 0 terminal mode off 1 terminal mode on In terminal mode ACK and NACK are not sent and OK or error response is sent for all valid commands that do not otherwise generate a response TIMEout Set query timeout in seconds password protected 0 lt timeout gt timeout disabled 1200 will go to unconnected state if no valid message is received in the timeout period ERRor Query the next error in the error event queue FREQUENCY Set the dominant noise frequency Hz to be suppressed Hz in the calibration routine This will generally be the line frequency 50 or 60 PASS word pass Set query the administrator password lt pass gt to allow access to protected functions The default is lt 12345 gt SAFEstate 011 Set query whether the I200 goes to the safe state when unconnected 0 do not go to safe state 1 go to safe state Safe state is HV off SERIALnumber Set query the serial number lt serial gt of the I200 max lt serial gt 10 alphanumeric characters Password protected VERSion Query the SCPI standard version TRIGger COUNt Query the trigger count since the last INITiate DELAY delay Set query the trigger delay for message trigger mode This parameter permits all devices on a loop to start an acquisition at the same ti
8. 1200 Dual Current Integrator with Servo Control Option User Manual Pyramid Technical Consultants Inc 1050 Waltham Street Suite 200 Lexington MA 02421 USA US TEL 781 402 1700 FAX 781 402 1750 EMAIL SUPPORT PTCUSA COM Europe TEL 44 1273 493590 PSI System Controls and Diagnostics 1 Contents 1 jU 2 2 rui cp M H A 7 3 eris ure 9 4 a EO L C C A A A EA E C P 11 5 Scope URN VASTE E E M 12 6 Optional Items eese 13 Ok JPowersuppliesuz ie T EO REOR eee ees Ue ee IERI 13 6 2 Signal cables and cable accessories esee esee nennen nent eem ennt enne tentent ene 13 0 3 JData CObleSs etie efe ete ett tete ot evecta e eue e efto dele ted eds 13 6 4 Fiber Opte loop res on RR ERE RERUM ERAS TREE ND a as 14 7 Intended Use and Key Features eerie ee eee eee eese eee eene tenens etna etna etna tss tas sense ta seta seen s eese ts etos sense ense en sene 15 Zel Intended EE 15 2 KY KEUNE S oree tet iste ql die ye to ite tete EE T EERE 16 8 SPECICATION Eee EC m 17 9 How the I200 Works an Overview eeeeeeeeee eere e ete te serene tatnen stata tne ta tatnen tasas tatnen stats ene ta tasse tatnen etant 21 9 Current meas
9. Page 77 of 119 PSI System Controls and Diagnostics 18 3 Front panel indicators 18 3 1 HV on Red LED The HV supply is enabled 18 4 Rear panel indicators 18 4 4 24V Green LED 24VDC power is present 5V DC DC converter is running 18 4 2 USB Green LED USB communication is active 18 4 3 RS 232 Green LED RS 232 communication is active 18 4 4 Optical Green LED Fiber optic communication is active 18 4 5 Xmit Green LED Data being transmitted from outgoing message buffer 18 4 6 Rcv Green LED Data being received into the incoming message buffer 1200 User Manual 1200 UM 110905 Page 78 of 119 PSI System Controls and Diagnostics 18 4 7 Status Red Green LED This LED indicates a variety of internal states as follows Alternating red orange green off Unit powering up Off Unit idle not measuring Orange Waiting for trigger or resetting integrators Green Integrating Red Error Alternating green orange EE Downloading program from host 18 4 8 Link Red Green LED This LED indicates a variety of communication states as follows Alternating red orange green off Unit powering up Off No connection since last power up Alternating green off Unconnected Alternating orange off Unconnected unit has gone to the safe state Green Connected Red Fatal communications error TAADA Fast alter
10. Query which device is listener 1200 User Manual 1200 UM 110905 Page 85 of 119 PSI System Controls and Diagnostics 20 2 3 2 IEEE 488 2 MANDATORY COMMANDS Commands which have a query equivalent for readback are marked with in the following table Parameters are generally passed to the I200 with the set version of the command but no parameters are passed for the query version For example ESE 3 set the Event Status Enable register to 0000011 ESE query the Event Status Enable register CLS Clear Status Command Clear all event registers and the error queue ESE Program query the state of the Event Status Enable register 8 bits I200 returns decimal value ESR Standard Event Status Register Query Query the state of the Event Status register I200 returns decimal value IDN Identification Query I200 returns manufacturer model number serial number firmware version OPC Set query the Operation Complete bit in the Standard Event Status Register after all pending commands have been executed Not currently supported RST Reset Command Return the device to the RST default conditions SRE Program query the Service Request Enable register Not currently supported STB Read Status Byte Query Query the Status Byte Register I200 returns decimal value TST Self Test Query Perform a checksum test on ROM and return the result I200 returns 1 WAI Wait to
11. 1200 User Manual Il200 UM 110905 Page 82 of 119 PSI System Controls and Diagnostics 20 2 ASCII Protocol SCPI Standard Commands for Programmable Instruments SCPI is an extension of the IEEE 488 2 standard This was originally developed by Hewlett Packard for the HP IB later GP IB interface before being adopted by the IEEE and is widely used by manufacturers of measurement equipment The I200 implements the 1999 0 revision of SCPI O 1999 SCPI Consortium 20 2 1 Messages The first bit of every eight bit group in a message is the start bit followed by seven bits encoding a character from the ASCII character set A full command from the host to the I200 comprises as many ASCII characters as needed to form the message terminated by the LF 0x0A character The I200 will not start to process a command until the OxOA character is received The list of valid commands is listed in the next section If the communications is being handled in a terminal session the terminal program should send CR 0x0d before the LF to get a legible display The CR is ignored by the command interpreter in the I200 The I200 generates a reply to every message from the host when it is the listener The first byte of its reply will always be a single non printing character The first character is ACK 0x06 when the command has been successfully executed with no errors Responses to host commands with a will then have the required data terminat
12. Example measured internal waveforms Timing diagram for continuous current monitoring The deadtime for setup reset and settle t is shown relatively large for clarity Readings recorded as charge Readings recorded as current 19 20 21 21 22 22 23 23 27 28 29 30 30 32 34 34 35 36 37 38 39 40 45 46 48 51 52 53 54 54 Figure 31 Illustration of integrator voltage at ADC sampling points during charge accumulation The reset periods are shown relatively large Figure 32 Figure 33 Figure 34 Figure 35 Figure 36 Figure 37 Figure 38 Figure 39 Example of an external start triggered measurement sequence started by a rising edge Figure 40 Example of an external start stop triggered measurement sequence started by a rising edge and ended by a falling edge Figure 41 Figure 42 Figure 43 Figure 44 Figure 45 Figure 46 Switching sequence for the no lost charge method No lost charge timing diagram Pulse input used to create a one shot current pulse signal for the 1200 Example of single shot time resolved data captured by the 1200 in fast mode Dataflow in ASCII mode Dataflow in binary mode without A500 Dataflow in fast binary mode with A500 Example of an external start hold triggered measurement sequence An integration showing signal and noise contributions to the final output Current compliance of the 1000V high volta
13. Figure 19 Figure 20 Figure 21 Figure 22 Figure 23 Figure 24 Figure 25 Figure 26 Figure 27 Figure 28 Figure 29 Figure 30 1200 chassis end panels Dimensions mm 1200 case side and plan views above Dimensions mm 1200 simplified block diagram 1200 integration an example current to be measured 1200 integration voltage on a capacitor that is connected at time zero 1200 integration capturing the voltage at two times 1200 integration discharging the integration capacitor and starting a new cycle Figure 8 1200 integration repeated integrations to sample a continuous current signal Path of measured current coax inputs RS232 connection cable from the 1200 to a PC serial port DB9 Hyperterminal COM port setup Hyperterminal terminal settings Example Hyperterminal session terminal mode Direct RS 232 connection to the 1200 Direct USB connection to the 1200 PSI Diagnostic Search Utility PSI Diagnostic Data current tab PSI Diagnostic Setup tab showing default settings Internal calibration current routed to channel 2 bargraph display format Device tab showing firmware update utility controls Data PID tab showing DAC output and PI servo controls The basic gated integrator circuit Data acquisition timing diagram 1200 block schematic Programmable times for the integrator reset process
14. Sw2 V t AVEO WV Ltt FL d o dM dM _ t per effective per Charge injection from Cs Figure 33 No lost charge timing diagram 1200 User Manual l200 UM 110905 Page 57 of 119 PSI System Controls and Diagnostics 14 8 Time Resolved Measurements 14 8 1 Standard Mode and FastMode The I200 can operate in two data transfer modes according to the type of host system it is communicating with Standard mode The I200 generates readings at the rate dictated by the integration time subsample count and reset parameters The host system collects these readings converted to amps or coulombs by the I200 at the rate allowed by the host software and the communications link Any readings which are not collected before the next reading overwrites them are lost Standard mode communications can be by ASCII or binary messages with binary more efficient and thus faster The readings are translated to using the stored calibration FastMode FastMode is only available in combination with the Pyramid Technical Consultants Inc A500 real time controller It is automatically selected with the first initiate command for all running modes except all accumulation modes gated trigger mode and message trigger mode If you are using the PSI Diagnostic host software there is a LED display on the Data tab which shows that FastMode is in use FastMode permits use of integration
15. Try the following tests to become familiar with the I200 Click the Calibrate button After a few seconds you should see the gain factors updated Click the calibration current button and select a channel If you return to the data tab you should see the 500 nA calibration current on that channel Try moving it to the other channel If the calibration current is overrange current reading is shown in red text reduce the integration period to bring it into range 1200 User Manual 1200 UM 110905 Page 37 of 119 PSI System Controls and Diagnostics amp PSI Loop Diagnostic v3 00 max Actions Window Help ela o0 o amp 1200 4 Address 4 on Loop 1 on A500 192 168 2 3 100 JIE Comms I Connected Pending Error Data Current PID x Initiate Measuring 1E 06 EE Q9 Triggering Abort 8E 07 Gated 6E 07 Current mA 46 07 P0156 26 07 Pam 499 854 ro oI Triggers 20344 Zero 4E 07 Se Clear 2E 07 Averaging Reset 1x Se DAC V ADC V 1E 06 f D 1 1 1 0 0 5 1 15 1 9969 0 0000 ENIE Y Range XTime kB Buffer Couple Mode Run Digitals i J100 Fast 9217 gt cir Fire DC i Ow S ox Last Error 6E 07 8E 07 Figure 20 Internal calibration current routed to channel 2 bargraph display format With the small value feedback c
16. 16 bit 0 to 10V output for process control The output can be commanded directly or placed under servo control using an error value derived from the current inputs The servo is executed in the microcontroller using floating point arithmetic Further details on the servo control option can be found in section 22 1200 User Manual 1200 UM 110905 Page 49 of 119 PSI System Controls and Diagnostics Making Measurements 14 4 Current and charge ranges The I200 measures the charge q that in integrated on the feedback capacitor The exact integration time tper is returned with every reading so the values are simply converted to the average current during the integration from The selection of feedback capacitor integration period and programmable gain amplifier setting determines the maximum current imax that can be measured limited by the ten volt range of the input amplifier LH P The table gives the nominal full scale measurement ranges for the standard feedback capacitors and three example integration periods You are of course free to select any integration period in the available span 20 usec to 10 sec The actual full scale ranges will differ slightly from channel to channel due to the small conversion gain variation due in turn to small differences in the feedback capacitor values that is compensated by the I200 calibration factors Which ranges are useful will of course be limited by the offsets and noise levels in
17. 50E 09 5 00E 09 3 4 50E 09 o 2 8 4 00E 09 a 3 50E 09 3 00E 09 0 10 20 30 40 50 60 Time Process target Process actual Figure 55 Example system response with no servo 1200 User Manual 1200 UM 110905 Page 106 of 119 PSI System Controls and Diagnostics If we now introduce some integral term the system starts to respond to the perturbations 5 50E 09 5 00E 09 4 50E 09 4 00E 09 Process value 3 50E 09 3 00E 09 20 30 40 50 Time Process target Process actual 60 Figure 56 System response with integral servo term Increasing the integral term leads to some oscillation due to phase lag in the system 5 50E 09 5 00E 09 4 50E 09 4 00E 09 Process value 3 50E 09 3 00E 09 20 30 40 50 Time Process target Process actual 60 Figure 57 System response with excessive integral servo term Adding some proportional term damps the oscillation 1200 User Manual 1200_UM_110905 Page 107 of 119 PSI System Controls and Diagnostics 5 50E 09 5 00E 09 3 4 50E 09 D 8 4 00E 09 a 3 50E 09 3 00E 09 0 10 20 30 40 50 Time Process target Process actual 60 Figure 58 System response with integral and proportional servo terms Both terms can now be increased in steps until a tendency for instabi
18. A Technical Consultants Inc PSI Diagnostic v2 60 Select Ports for Autodetect O Below Add IP Remove IP Figure 17 PSI Diagnostic Search Utility A few seconds after you click the Start button the program should find the I200 plus any other devices Clicking on the I200 entry in the explorer list will open the I200 window figure 18 In the figure the I200 is connected via an A500 controller rather than directly via USB The device will be acquiring data using default settings and you should see background noise values for both channels You can display the signals either as a scrolling current against time graph like a chart recorder or as an analog bargraph If the I200 is not acquiring data click the Initiate button to start the acquisition Toggle to one of the fixed Y scales if you want to inhibit autoscaling of the graph 1200 User Manual 1200 UM 110905 Page 35 of 119 PSI System Controls and Diagnostics i PSI Loop Diagnostic v3 00 Actions Window Help elb eo o amp 1200 4 Address 4 on Loop 1 on A500 192 168 2 3 100 Data ji Current PID Comms sesieiee 5E 10 4E 10 3E 10 2E 10 1E 10 0 AE 10 2E 10 3E 10 4E 10 5E 10 0 28634 03 0 35 0 39534 Y Renge XTime kB Buffer Couple Mode Run Cir Auto v Fast 4m l Fie oe Tees Connected Pending
19. Continue Command Wait until all previous commands are executed Not currently supported 1200 User Manual 1200 UM 110905 Page 86 of 119 PSI System Controls and Diagnostics 20 2 3 3 IEEE 488 2 OPTIONAL COMMANDS RCL Recall instrument state from EEPROM SAV Save present instrument state to EEPROM The settings covered by RCL and SAV are SOURce CONFig ACCumulation CAPacitor PERiod CONFig GATe EXTernal POLarity TRIGGER SOURce TRIGger POlInts Note that the high voltage settings CONFigure HIVOltage are NOT included 1200 User Manual 1200 UM 110905 Page 87 of 119 PSI System Controls and Diagnostics 20 2 3 4 1200 COMMANDS READ commands force an acquisition and return the data when it completes and therefore the data is new FETCh commands get the most recent value in the I200 internal buffer which may or may not be new data I200 set commands which have a query equivalent for readback are marked with in the following table Parameters are generally passed to the I200 with the set command but no parameters are passed for the query version For example CONF GAT INT PER le 3 5 set the integration period to 1 msec with five sub samples CONF GAT INT PER query the integration period and number of subsamples ABORt Abort measurement CALIBration GAIn CLEar Calibrate query gain for each channel or reset
20. DAC starting V 3f DAC present V 3f Monitor ADC V Ae Measured process value f I1 I2 Ae Target process value f I1 I2 4e Sum of TargetProcessValue ActualProcessValue Ae Following error TargetProcessValue ActualProcessValue d Error state 0x01 if DAC limit hit 0x02 if data invalid or current low limit hit PROFile S1 option only Read the next profile data point if not available then DataNotAvailable error is returned Ae Measured process value f I1 I2 4f Monitor ADC voltage READ Do same READ command as previous defaults to charge if no previous STATus OPERation CONDition Query operation register status condition bit ENABlIe Q Set query operation register status enable bit EVENGC Query operation register status event bit QUEStionable CONDition Query questionable register status condition bit ENABlIe Set query questionable register status enable bit EVENGC Query questionable register status event bit SYSTem COMMunication CHECKsum 011 Set appending checksum to all replies password protected 0 off 1 on IDENTIFY Sends chained identify command Devices in the loop combine to assemble the response number of devices 1200 User Manual 1200 UM 110905 Page 92 of 119 PSI System Controls and Diagnostics in loop addr of first device addr of second device
21. Manufacturer Location PTCI200 3120 PTC c windows inf oem42 inf Bl A This driver is not digitally signed Teil me why driver signing is important lt Back Cancel If there is only one valid entry the wizard will proceed directly to the installation phase 4 Allow the installation to continue despite the driver not having the Windows Logo approval Hardware Installation a The software you are installing for this hardware PTC 1200 has not passed Windows Logo testing to verify its compatibility with Windows XP Tell me why this testing is important Continuing your installation of this software may impair or destabilize the correct operation of your system either immediately or in the future Microsoft strongly recommends that you stop this installation now and contact the hardware vendor for software that has passed Windows Logo testing Continue Anyway STOP Installation 5 The driver installation should now occur Found New Hardware Wizard Please wait while the wizard installs the software a E25 PTC 1200 EC E Setting a system restore point and backing up old files in case your system needs to be restored in the future 1200 User Manual Il200 UM 110905 Page 43 of 119 PSI System Controls and Diagnostics Found New Hardware Wizard SS Completing the Found New Hardware SY Wizard The wizard has finished installing the software for fe PTC 1200 Click Finish
22. USB are intended for direct connection to a host PC The fiber optic interface allows a full loop based system with multiple individually addressed devices Cal current Switchable test amp calibration source i i DC DO 24V DC in Switchable large feedback capacitor mo e Gate TTL lt Gate optical ll Serial USB use gt Ch 1 in FPGA A S Rses2 P 9 1 gt x H MUX ADC Fiber optic EIER e a RX Ch2 DAC Servo control in out Vv DAC 2x gated Y HV integrator HV o t Pau Divider ADC Micro lt Analog in controller ADC p Digital in Figure 25 1200 block schematic The two integrators are operated in synchronization The output voltages are multiplexed into the ADC in rapid succession to be digitzed by successive conversions The time offset between the two inputs is 4 microseconds Because the ADC conversions can occur much more rapidly that the integration period the I200 can use sub integration period sampling to track the charge build up on the feedback capacitors between resets as described in the previous section This enables several useful measurement techniques and features When the average
23. You can tell if the voltage is being pulled down by excessive current drain by watching for relative changes CAUTION Do not connect external power supplies to the I200 external high voltage output that will drive the built in supply away from the voltages it is trying to regulate or you may cause damage to the I200 CAUTION Do not connect the I200 signal inputs or the external high voltage output to electrodes in a system that will be subject to direct strike by high energy high current charged particle beams that will drive the built in supply above the voltage it is trying to regulate or you may cause damage to the I200 16 2 High voltage options The range and polarity of the high voltage supplies is fixed and must be specified at time of purchase The following HV options are available 1200 option Maximum voltage Current rating XP10 1000 1 mA XP5 500 2mA XP2 200 5 mA XN10 1000 mA XN5 500 2mA XN2 200 5mA Units may be returned to the factory to alter the high voltage modules It not recommended that users change the high voltage supply module CAUTION Incorrect jumper setting can result in the incorrect output voltage and no output voltage feedback The necessary configuration details are given here for reference 1200 User Manual Il200 UM 110905 Page 71 of 119 PSI System Controls and Diagnostics
24. be used but the lowest detectable current will be increased Pyramid Technical Consultants Inc does not recommend using the direct USB interface for very low current measurements Connecting the USB cable causes the chassis to connect to analog ground in the I200 which increases zero noise and drift Fiber optic interfacing is optimum for both speed and noise immunity 10 3 2 Signal cables If your I200 was supplied with the standard BNC inputs you should use low noise coaxial cable to connect to the signal source A cable which has been tested and found to give good immunity 1200 User Manual Il200 UM 110905 Page 27 of 119 PSI System Controls and Diagnostics to vibration induced noise is Belden 9223 010100 low noise RG 58 Normal coaxial cable should not be used as this will degrade significantly your ability to measure small currents If your I200 was supplied with the triaxial connector option you should use triaxial cable A recommended type is Trompeter TRC 50 2 Three lug triaxial connectors are used on the I200 The signal core and the inner guard screen are at internal analog ground potential with the connection made in the I200 The shared potential of the guard and signal conductor are important for minimization of leakage currents and triboelectric noise The outer screen is at I200 chassis potential The inner guard should be brought as close as possible to the point of connection to the signal source but should
25. current being measured is very low so that a long integration period is needed to get a precise value sub integration sampling allows intermediate current values to be returned rather than having to wait for the integration to end before getting a new reading Time resolved data is available from within the integration period This allows given adequate signal to noise ratio reconstruction of the shape of a pulse that occurred within one integration period 1200 User Manual Il200 UM 110905 Page 48 of 119 PSI System Controls and Diagnostics A precision 500 nA calibration current source is built in to the I200 It can be switched into either channel Confirmation of correct operation and gain calibration can be performed under remote control Each integrator circuit has a FET switch in series in its input in addition to the reset switch in its feedback loop Operation of this switch in combination with the reset switch allows an integration mode where no charge is missed even during resets This is described in the section on charge accumulation measurements The on board processor can monitor several additional parameters as well as the integrator outputs External auxiliary HV output via a voltage divider Two opto coupled digital input lines Analog input to a 10 bit ADC buffered and scaled to read 0 10V from a pin on the auxiliary I connector The I200 S1 servo control version provides a high precision buffered
26. it may be beneficial to reduce the settle reset and settle times below their nominal values until you notice an unacceptable degradation in accuracy and precision 14 6 Continuous Current or Charge Measurement The I200 returns charge readings to its host plus the time over which the charge was integrated The data can thus be presented as charge or current By continuous repetition of the measurement the I200 can make a continuous reading of the current or charge on its inputs In this mode it behaves like a sensitive current to voltage converter The input current can be positive or negative A positive reading represents conventional current flowing into the I200 A negative reading represents conventional current flowing out of the I200 WAR NOAA POS PN i t Sw2 1 M M V t Figure 28 Timing diagram for continuous current monitoring The deadtime for setup reset and settle t r s is shown relatively large for clarity Repeated integrations of the specified period tper are made Each integration yields start and end ADC values plus interim charge values from any sub integration sampling that has been requested The PSI Diagnostic host allows you to record data directly as charge Figure 29 1200 User Manual I200_UM_110905 Page 53 of 119 PSI System Controls and Diagnostics shows an example of this for a case with five 20 usec subsamples in each of three 100 usec integrations while measur
27. most appropriate when you require the minimum sub microsecond and most consistent delay between the trigger and the start of integration The selection of the active trigger input is via a software command the default is the BNC The sense of the logic is a software configurable parameter The BNC input requires a TTL level and presents a TTL gate impedance To avoid spurious signals due to noise we recommend that you fit a 50 ohm terminator to this input if you are not using it If your trigger source is able to drive a 50 ohm load we also recommend this termination if you are using the input to guarantee clean trigger edges The fiber optic input requires an on off light 640 nm nominal wavelength If you do not intend to use the optical trigger input you should ensure it is not selected to avoid accidental triggers from ambient light or fit a blanking plug Message triggering provides similar performance to the external modes but with slightly greater delay In looped systems the loop controller knows the position of each device in the loop and arranges for each device on the loop responding to the trigger to delay its response according to its position in the loop so that all devices start their acquisitions at the same time 1200 User Manual 1200 UM 110905 Page 64 of 119 PSI System Controls and Diagnostics 14 9 7 Illustrations of external triggers Figure 39 is a schematic example showing an external start trigg
28. the reset settle and setup times password lt settle gt lt setup gt protected HIVOltage ENAble Query the high voltage enable state 0 all HV off 1 external or signal bias HV on EXTernal MAXvalue Set query maximum allowable external high voltage volts setting password protected VOLTs volts Set query the external high voltage PID MODe 011121314 S1 option only Set query the PID mode where 1zlI 2zII4D2 3zII D 4 1 12 5 I1 IDD I1 H2 RATe lt per gt S1 option only Set query the PID servo period 5 to 255 msec LIMit lt limlo gt Set servo DAC output low limit lt limlo gt and high limit lt limhi gt lt limhi gt 0 to 10 0 V 1 I2LOW lt curr gt S1 option only Set query the sum of the two input currents lt curr gt amps below which the servo will be suspended KP lt prop gt CSI option only Set query the servo proportional term prop KI int S1 option only Set query the servo integral term 1200 User Manual 1200 UM 110905 Page 89 of 119 PSI System Controls and Diagnostics int PROFile LIMit lt prflo gt lt prfhi gt 2 S1 option only Set query the DAC start lt prflo gt and end lt prfhi gt points for the automatic profile sweep 0 to 10 0 V POINts 2 S1 option only Set query the number of data points for the automatic prOf
29. to close the wizard When installation is complete the Your new hardware is installed and ready to use message balloon should appear You may be prompted to reboot your PC Note that Windows XP recognizes each individual 200 as a different device because it has a unique serial number Therefore you will be prompted to install the driver again if you connect another I200 Simply repeat the process outlined above 13 2 Windows 7 Installation Differences Windows 7 has a more automated driver installation process which searches the internet and your computer for an suitable driver If you have installed other Pyramid Technical Consultants USB devices in the past on the computer Windows 7 will usually recognize that the same driver is appropriate Otherwise you will need to direct it to the driver location With the I200 connected to a USB port open Device Manager and find the I200 under Universal Serial Bus controllers Double click to open the Properties dialog and select Update Driver You can then navigate to the correct directory and install the driver If you do not see the I200 in the list of devices this may mean that the FTDI chip is not programmed with the correct PID You can still use the USB port Look for the FTDI Serial Converter device in the list and proceed as above 1200 User Manual l200 UM 110905 Page 44 of 119 PSI System Controls and Diagnostics 14 Principle of Operation 14 1 Gated Integrator
30. understand this is to look at a practical example For the example an I200 input was driven with a pulse from a function generator with the characteristic shape shown in figure 34 This was converted to current with a peak value of 18 nA using a 10 Mohm resistor 1200 User Manual 1200_UM_110905 Page 58 of 119 PSI System Controls and Diagnostics IM Pos 1 10 rms SAVE REC Action Save Image File Format JPEG M SOO us Figure 34 Pulse input used to create a one shot current pulse signal for the 1200 In order to sample this waveform with the highest possible time resolution and no deadtime a single integration with a large number of subsamples was used The I200 was set to capture 250 subsamples over a 5 msec integration and thus a subsample period of 20 usec using an external trigger from the signal generator The resulting captured waveform is shown in figure 35 1200 User Manual 1200_UM_110905 Page 59 of 119 PSI System Controls and Diagnostics 4 1200 1 Address 1 on Loop 1 on A500 192 168 100 200 100 cmn x Comms ff Connected Pending Error Data Current PID Measuring Initiate Triggerin 2E 08 rogenng Abort Fast Mode Gated 1 5E 08 l Current v nA gt 1E 08 ms w EENNNEETS 5E 09 001 T s Triggers 250 5E 09 Zero Set Clar 1E 08 Averaging h m A5E 08 Reset x vj DAC V ADC V 2E 08 E 7452E 05 0 002 0 00
31. x pF and y pF default is C10 1000 Options for x are 10 30 60 100 y values from 100 to 3300 100AB Add 100x unequal conversion gains option for the input channels S1 Add multi mode servo option TRIAX Signal inputs on 3 lug triax connectors default is BNC Example I200 XP10 S1 100AB 1200 User Manual 1200 with standard BNC signal connectors with options 1000V positive auxiliary bias output selectable 100x gain difference on the multimode servo option 1200_UM_110905 Page 11 of 119 PSI System Controls and Diagnostics 5 Scope of Supply I200 model as specified in your order Plug pack 24 VDC power supply PSU24 45 1 Serial cable adaptor AB450K R USB memory stick containing User manual PSI Diagnostic software guide PSI diagnostic software files USB drivers and utilities Optional items as specified in your order 1200 User Manual Il200 UM 110905 Page 12 of 119 PSI System Controls and Diagnostics 6 Optional Items 6 1 Power supplies PSU24 45 1 424 VDC 1 88 A PSU 100 250 VAC 50 60 Hz IEC C14 3 pin plug receptacle with output lead terminated in 2 1mm threaded jack PSU24 36 1 24 VDC 1 5 A PSU 100 250 VAC 50 60 Hz IEC C8 2 pin plug receptacle with output lead terminated in 2 1 mm threaded jack 6 2 Signal cables and cable accessories CAB BNC colo Cable coaxial low noise BNC plug to BNC plug 3 lug 3 m CAB SHV CO 3 SHV Cable coaxial SHV to SHV 3m ADBJ77 E2
32. 0 Dual Charge Integrator Year of initial manufacture 2007 Applicable Directives 73 23 EEC Low Voltage Directive Laws for electrical equipment within certain voltage limits 89 336 EEC EMC Directive Laws relating to electromagnetic compatibility Applicable Standards IEC 610101 2002 2 Edition UL 61010 1 2004 EN 61326 1997 A1 1998 A2 2001 EN 55011 1998 A2 2002 EN 61000 6 2 2001 Electromagnetic Compatibility Generic Standard Immunity for Industrial Applications Issuing Agencies Safety TUV Rheinland North America 12 Commerce Rd Newtown CT 06470 USA EMC TUV Rheinland North America 12 Commerce Rd Newtown CT 06470 USA Applicable Markings TUV FCC CE Authorized by p President Pyramid Technical Consultants Inc Date i Apr O8 The Technical Construction File required by theses Directives are maintained at the offices of Pyramid Technical Consultants Inc 1050 Waltham Street Lexington MA 02421 USA A copy of this file is available within the EU at the offices of Pyramid Technical Consultants Europe Ltd 2 Chanctonbury View Henfield BN5 9TW United Kingdom 1200 User Manual I200 UM 110905 Page 118 of 119 PSI System Controls and Diagnostics 30 Revision History The release date of a Pyramid Technical Consultants Inc user manual can be determined from the document file name where it is encoded yymmdd For example I200 UM 080105 would be an I200 manual released on 5 January 20
33. 0 kohm Thus up to 100 uA is available at 30 V output 200 uA at 60 V output and so on At higher outputs it is limited to 1 mA maximum HV modules with lower voltage rating can be specified at the time of order which provide correspondingly greater current compliance A Q Q o Q eo Unavailable AB Q o Operating region T o o E S 600 o o 2 9 E o bj e o o 50 100 150 200 250 300 350 400 Voltage setting V Figure 43 Current compliance of the 1000V high voltage supplies 1200 User Manual Il200 UM 110905 Page 70 of 119 PSI System Controls and Diagnostics Positive supplies source conventional current and negative supplies sink conventional current A 25 Mohm bleed resistor fixed load is connected to each high voltage supply output which drains 40 uA at maximum voltage from the 1000V supply Transorb protection devices prevent the absolute value voltage at the output going more than 80 V above the maximum rating However these devices are not designed to pass large currents indefinitely so you should be careful not to overdrive the outputs with other power supplies or with charged particle beam strike currents The output voltage is monitored by a 10 bit ADC and the value can be displayed by the host software The monitor value is not used for control or feedback purposes It is of relatively low accuracy and is only intended for confirmation that HV output is being generated
34. 08 Version Changes I200 UM 071205 First general release I200 UM 080721 Default signal connectors changed from triaxial to coaxial ExternalGate trigger mode removed CE conformance certificate added I200 UM 080821 Descriptions and examples of 20 usec time resolution added I200 UM 100526 Add VOLTage command missed from ASCII list Add section on disposal I200 UM 110905 Add Overview section Add description of servo process parameter normalization Add section on 100AB option 1200 User Manual 1200_UM_110905 Page 119 of 119
35. 3 2 Windows 7 Installation Differences esee nene nrenne eren entente trennen 44 14 Principle of ciagivt cr M 45 14 1 Gated Integrators cou tedce o RR UE dm t DEDE 45 14 2 Sub sa mpling eR ele i etse edt m ee e n he e e tede e a Aa es 46 14 3 1200 Circuit OVekEVIeW isi ee Rte ee REA RENE E RR ae URN vn ew e RETE PAUSE 48 Making FEES MIS PET 50 14 4 Current and charge Wangess sii uti e i hee ete e a eire 50 14 5 Integrator COnttOl i rp bep pe m umi 51 14 6 Continuous Current or Charge Measurement eese eene tette nennen rene nennen rennen 53 14 7 Charge Accumulation Modes iae re rte HE EO ER EE Ee v rr SE Ha 55 14 7 1 INO res t time correction ne ee e e epe E te i Genet coda dade 55 14 7 2 Reset time interpolation sisisi iiir eii tete v dee e bU cade edu ep eed eee eaa eee ae veut 55 14 7 3 Lossless accumulation technique essent enne nennen rennen eren eren 56 14 8 Time Resolved Measurements ie te des ter eret eae e Eee nt e Eo ER E ee eee Teens 58 14 8 1 Standard Mode and FastMode tede e HR eee pee retenta 58 14 8 2 Example of single shot time resolved data capture at high rate sese 58 14 9 Data Readout and Buffering oett eet ie rer ee eer ERRER 60 14 9 1 Data readout and buffering in ASCII mode sees eene n
36. 4 0 005025 0 0000 0 0000 Y Range X Time kB Buffer Couple Mode Run Digitals 100 lFast 250 gt cw Fie vc sro M OpoA 6 OpoB Last Error 5 09 09 PM FETCHMONITOR 902 Timeout Figure 35 Example of single shot time resolved data captured by the I200 in fast mode Note that the ability to take time resolved data is limited ultimately by signal to noise ratio and the frequency components of the noise At short integration or sub sample periods lower frequency noise components are not averaged so you may end up with nothing more than good time resolved noise if there is insufficient signal and or your noise levels are high 14 9 Data Readout and Buffering 14 9 1 Data readout and buffering in ASCII mode In ASCII mode the ADC readings are converted to floating point numbers in coulombs by application of the calibration in the I200 The value for each channel requires 12 bytes and the integration time and the overrange byte add to this to give a message size for reading out both channels of 37 bytes The maximum data rate to the host is 3 Mbps via USB and 115 kbps via RS 232 so the transmission time for the data is in the range 0 1 to several milliseconds The data rate will generally be less than this implies because the host must send messages on the same fiber optic channel and there may be other devices if you are using a loop topology 1200 User Manual 1200 UM 110905 Page
37. 60 of 119 PSI System Controls and Diagnostics 1200 Host system Calibration EM t iy lo float or COM handler t qi q2 float Figure 36 Dataflow in ASCII mode If data is generated by the I200 at a higher rate than the maximum available transmission rate then samples that cannot be transmitted are discarded Because each 2 channel sample is given a sequential index number corresponding to each trigger you can see if any samples have been lost by examining the data In the basic application of monitoring a slowly varying current with random noise components such missing data is of little consequence However if you are attempting to capture a transient event then this is likely to be unacceptable and you should use a higher bandwidth communication protocol and interface 14 9 2 Data readout and buffering in binary mode Binary mode provides higher performance especially when the I200 is connected to a real time controller such as the A500 Each channel requires four bytes which represent the charge value and the maximum communication speed using the fiber optic loop is 10 Mbps so data rates can be 5 to 10 times faster than the best that can be achieved in ASCII mode Values are sent up to the host as they are generated 1200 Host system Calibration t dy q2 t q q BIN A float Figure 37 Dataflow in binary mode without A500 The
38. 9 PSI System Controls and Diagnostics circuit very low relative to setpoint Monitor value recovers if I200 disconnected from the external circuit Cannot set high voltage Trying to set above the maximum allowed value soft limit Sets OK if a lower value is chosen If allowed increase the maximum allowed value Unable to communicate with I200 Wrong mode switch or address setting Check mode switch setting against table in section 16 and address against expected address in host software Use correct switch settings Switches can be changed while the unit is operating Unable to connect on fiber Connector still fitted to RS232 Remove RS232 and USB loop or USB connectors Communications interruptions Other processes on PC host Use a dedicated PC with interfering with comms ports simple configuration and minimum number of processes running Unable to connect on USB Missing or incorrect USB driver Device connected tone not heard when connecting the USB cable Install correct driver Refer to the I200 Software Manual Unable to connect on RS232 Another program is using the COM port Try to access the required port with Windows Hyperterminal Choose another port or close down the other program Incorrect port settings Try to connect with the htm file supplied with the unit Correct the settings Incorrect cable Make u
39. A500 has the capability to buffer a sequence of over a million values Depending upon the loading of the communication channel the integration period may be as short as 100 usec with no lost data 14 9 3 Data readout and buffering in FastMode In FastMode the translation to coulombs is performed by the A500 using the calibration data uploaded from the I200 This process is transparent to the host computer In this mode it is also possible to buffer up to 768 samples in the I200 itself which allows contiguous sub sampled data with periods down to 20 usec in all circumstances This is the highest available time resolution and can be used The A500 can also buffer over one million samples in its own memory which may be contiguous data if the data transfer rate from I200 to A500 is greater than the rate at which data is generated by the I200 If the I200 is the only device running on a fiber optic loop then this can be achieved at 20 usec 1200 User Manual Il200 UM 110905 Page 61 of 119 PSI System Controls and Diagnostics 1200 FPGA Buffer BIN t ADC ADC Calibration 4500 t dy q2 float Figure 38 Dataflow in fast binary mode with A500 1200 User Manual l200 UM 110905 Host system t qi q2 float Page 62 of 119 PSI System Controls and Diagnostics 14 9 4 Triggering 14 9 5 Triggering trigger points and measurement timing Every measure
40. Diagnostics 16 High Voltage Supply 16 1 Setting the high voltage The range and polarity of the high voltage supply is fixed and must be specified at time of purchase Units may be returned to the factory to alter the high voltage modules if necessary The set value can be adjusted at any time independent of what measurements are in progress Any valid setpoint above zero volts enables the supply The HV on LED illuminates when the supply is enabled Each supply is limited by a software high voltage limit which is password protected and stored in EEPROM in the I200 The I200 will reject any attempts to set the voltage higher than the limit This allows sensitive detector systems or experiments which may be damaged by excessive voltage to be protected CAUTION Note that the HV modules are not designed to operate below 10 of their maximum rating They will regulate at lower voltages than this but at startup you may see the voltage overshoot considerably before it settles to the setpoint over a period of a few seconds This happens irrespective of any high voltage limit you have set Always specify an HV module option that matches the requirements of your sensor system The maximum current compliance of the high voltage power supplies depends upon the output voltage At low outputs the compliance of the 1000V high voltage supplies for example can be represented as the current that the voltage would cause to flow in a resistor of about 30
41. E 12 4 1 0E 12 4 0 0E 00 1 0E 12 Chi ion chmbr Ch2 no signal Figure 50 Separation of a 5 pA signal from background integration periods 1 msec 0 1 sec and 10 sec Where there are known dominant noise frequencies in current measurements for example line voltage interference these can be suppressed by choosing an integration periods that is an integer multiple of the noise period For example 50 Hz or 60 Hz noise from the power line is present in most environments This can be completely removed in the I200 by selecting the integration period as follows Noise frequency Integration period choices to eliminate noise 50Hz 20 00 40 00 60 00 80 00 100 00 K x 20 00 msec 60 Hz 16 67 33 33 50 00 66 67 83 33 100 00 K x 16 67 msec Note that 100 msec is a useful integration time because it suppresses both 50 Hz and 60 Hz noise Very small charge package measurements should be optimized by synchronizing the integration carefully around the arrival of the charge This minimizes the amount of background offset current that is included in the reading Often the arrival of the charge is associated with an event in the system which can be used to drive the external gate input of the I200 to obtain the required synchronization 21 7 Summary Factor Typical noise Mitigation Typical noise offset current after mitigation Triboelectric effects in 10 A Reduce cable le
42. Error 19 Measuring Triggering Gated Triggers 1982 Digitals x nA Zero Set Clear Averaging Reset 1x DAC V ADC V 0 000 EE OptoB OptcA Figure 18 PSI Diagnostic Data current tab 5 Click on the Setup tab Here you can adjust measurement parameters such as integration period feedback capacitor set the auxiliary high voltage and use the built in calibration facility 1200 User Manual 1200_UM_110905 Page 36 of 119 PSI System Controls and Diagnostics a PSI Loop Diagnostic v3 0X Actions Window Help leli o0 o A System IE Comms az pu Connected Pending Error Setup CONFiguration TRIGger CALIbration Calibrate Integration Period External Bias Source Culbralion Cunt 5 1 000E 004 s Max 1000V to ov d 500 nA Gate Polarity Save Ch 500 annel 1 Rage o om il 1000E 006 jA SetValue Maruti C2 9 0 r Trigger Points INFINITE INF Gain Factors Subsamples 10pF 1000pF 18 E cornet 2 NEN EE 91 1 C BNC amp Optical 2 EHE 2 Accumulate Mode None E r Reset Settle rCapacitr Command 10pF 1000pF 10 pF Reset 4o A ZT N seme 40 B Setup 20 ic Last Error Figure 19 PSI Diagnostic Setup tab showing default settings
43. Integrators are overrange Overrange flags are set signal recovers if integration period is reduced Reduce the integration period or use the larger feedback capacitor Measured currents or charges are inaccurate by up to 15 Unit not calibrated Calibrate Calibration was carried out while a signal current was present Internal calibration source does not measure as 500nA with all inputs disconnected Repeat calibration with no external signal present High background offset Various causes Refer to section 21 current 500 nA background on all Internal calibration source has Turn off calibration source channels been turned on I200 stops measuring Trigger points limit reached Measurement starts again if I200 is reinitialized Adjust trigger points as required Data buffer full Measurement starts again if I200 is reinitialized Adjust data points as required and or turn on data buffer wrap Communication link timeout Investigate and fix communications issue Use a longer timeout setting No or incorrect response to external trigger or gate Incorrect gate polarity selected Use correct polarity 1200 not configured to respond to external gate Use correct setup No high voltage Shorted to ground in external Monitor HV reading zero or Eliminate shorts to ground 1200 User Manual 1200_UM_110905 Page 112 of 11
44. ONDition or STATus QUESTionable CONDition as appropriate to recover the details from the relevant register You can use the I200 ASCII communications without using the status registers 1200 User Manual 1200 UM 110905 Page 83 of 119 PSI System Controls and Diagnostics Questionable Statu S Questionable Questionable Evert Condition Enable QUE Stionable Register Register i Structu re STAT u EVENt ENABle Standard Serwce Standard Event Status Request Event Status Byte Enable Status Enable Register Register Register Register Operation Complete Query Error Device Dependent Error Execution Error Command eror 5 HH S j User Request EGN oa Ha Power tn 7 FL j ESE E Error Anailable OSB Questionable Summary Bit MAM Message Aailable ESB Event Summary Bt Operation Operation ay Pusa hepatit ase Condition Event Enable OPERation Morlem pud 2 Register Register Register Calibrating Rangng Measuring Mating for Trigger Saving to EEPROM Program running CONDition EVENt ENABle Figure 45 SCPI Status register structure 1200 User Manual 1200 UM 110905 Page 84 of 119 PSI System Controls and Diagnostics 20 2 3 Host Commands The I200 responds to the mandatory commands prescribed by SCPI and IEEE 488 2 plus specific commands as required by the operation of the device The commands are grouped with a hierarchical structure with the level
45. PL20 Adaptor triax 3 lug jack to BNC plug Guard not connected through ADBJ20 E2 PL75 Adaptor BNC jack to triax 3 lug plug Guard not connected through RF175 1 Dust cap 3 lug triax SHV to SHV cable 3m 6 3 Data cables ABA450K R RS 232 6 pin DIN male to 9 pin D sub female adaptor 1200 User Manual 1200 UM 110905 Page 13 of 119 PSI System Controls and Diagnostics CAB ST P 5 ST qty two Fiber optic cable pair 5m plastic CAB ST HCS 5 ST qty two Fiber optic cable pair 5m silica 6 4 Fiber optic loop A200 USB to fiber optic adaptor A300 fiber optic loop controller Ethernet adaptor A500 intelligent cell controller with Ethernet interface 1200 User Manual 1200 UM 110905 Page 14 of 119 PSI System Controls and Diagnostics 7 Intended Use and Key Features 7 1 Intended Use The I200 is intended for the measurement of small charges or corresponding currents from pA to uA generated by devices such as ionization chambers in vacuum beam position monitors proportional chambers and photodiodes Two input channels make the I200 particularly well suited to split electrode systems used for beam centering The S1 option allows the I200 to function as a PID controller for applications where an analog voltage is used to control a process and the process variable is a function of the measured input currents In particular it is intended to control the crystal cages of double crystal monochrom
46. S 232 set the mode switch to position 2 115 kbps binary If you are using USB set it to position 1 3 Mbps binary The address switch can be set to anything between 1 and 15 1200 User Manual I200_UM_110905 Page 33 of 119 PSI System Controls and Diagnostics Mode switch setting 2 Mode switch setting 1 USB 24V in L N L_ a E Figure 16 Direct USB connection to the 1200 The Diagnostic will see this simple configuration as a loop with just a single device on it Because the direct RS 232 or USB connection does not allow other devices to be seen through that port the I200 appears as both a loop and a device on that loop Contrast this to the situation where you have a loop controller such as the Pyramid Technical Consultants Inc A200 A300 or A500 devices and the I200 is connected to the controller via a fiber optic loop In this case the loop controller is identified as the loop and the I200 as a device on the loop 4 Start the PSI Diagnostic It will search the available ports and present a search a list Figure 11 shows a case where the program found two serial ports a connected USB device the I200 and a local area network adaptor It will search for loops and devices on all checked options 1200 User Manual 1200 UM 110905 Page 34 of 119 PSI System Controls and Diagnostics amp PSI Loop Diagnostic v2 60 lees Actons Window Help Pl Bd 2 gt
47. U trt a 74 17 1 6 Ground US 23 5 Sunbeam Re ee GA Ra a 74 17 2 Rear Panel CONNECIOPS e eee ti ee I ea reete ed e e a Duane ete vee ev E Ue Cr Un eden 74 17 2 1 Power Imp m P nee e d ae d Hi caedi cH EA 74 17 2 2 USB coimmunications 4rd need e dte ente ere eie ERA t tae ee tete 74 17 2 3 RS 232 commiunic tlons o rp etie e PO Re D RE EG Rer peo 74 17 2 4 Fiber optic communications etse tart iere suds sondstesscouctesctevenessesvepbesendeuseesvacuveensteues 75 IEEMOOUUTPnr 76 18 1 Frontpanel controls d deer tt eiae etre E e E RERO SEC HERR QNT ERE Re ERES 76 18 2 Rear UT NsO soU a E 76 18 2 1 MOE SWICDL reete Else nu be en a e ec sepe toits 76 18 2 2 Address switchs dem ERR ee tete ES 77 18 3 Front panel indicato S oeiee irta TERREA RSV SR ERE URN EE ERE ves Decks ER GOYA en TWERN ER P ken 76 18 3 1 HV O eeta dette tet i tatit feti ete ott 78 1200 User Manual 1200 UM 110905 Page 4 of 119 PSI System Controls and Diagnostics 18 4 Rear panel indicators sci ovre etie t he ent i ab e e fce ye te yeah Gees 76 18 4 1 POA onere dede dut ete n dd 78 18 4 2 US Breanne been teo eta pido e tea aet A Ed E IU E INE 78 18 4 3 RS 232 3 nidos tede e tet ree tet ath ee Ree P ERO Penn 78 18 4 4 Optical he e eth ep ete ede M eie etr nt ees 78 18 4 5 Xm s eerta a v e e p RE RR TUE e EE e eret 78 18 4 6 i
48. ag X tper 15 2 Gain calibration The calibration gain factors convert charge into ADC output and thus are the composite of the feedback capacitor size buffer amplifier gain and ADC gain The 200 calibrates itself automatically on all channels by switching on the internal 500 00 nA current source and making measurements with known integration period IMPORTANT There must be no signal current flowing into the inputs when the calibration is taking place because it will add to the calibration current and give an incorrect result This incorrect calibration would not be detectable by checking the internal calibration source readback but only by measuring a known independent current source Because background offset current can affect the gain calibration process itself the I200 also makes a background measurement as part of the calibration cycle The measured background ADC difference is subtracted from the ADC difference measured with the calibration source on to get the net value that is equated to 500 nA The calibration factors are stored in the I200 in EEPROM when a save calibration command is issued They are then loaded automatically on power up The host computer can upload them for use in binary communication modes If there is no calibration available the I200 will use a nominal calibration and the measurements will be of reduced accuracy 1200 User Manual 1200 UM 110905 Page 69 of 119 PSI System Controls and
49. apacitor selected set an integration time of one second You should now see very low noise on both inputs a variation generally less than 0 1 pA Click on the Device tab You can check the communication link status and verify the versions of the hardware and firmware On the right is the firmware update utility You can use this to download firmware updates hex files downloaded from the Pyramid Technical Consultants Inc web site 1200 User Manual I200_UM_110905 Page 38 of 119 PSI System Controls and Diagnostics A oop Diagnostic v3 Actions Window Help lelua 00 o Comms p jcomedea Renang Error Device Communication SYSTem Properties Utilities r Messages Sent SAFES r Device Version Upload Application 14551 34 Select hex file EE HRS COMMTERM eA Ve Checksum Errors j SEn COMM CHECksum 944 Reset Device r Hardware Version Echo Errors 50 Hz 4 0 i SERIALnumber IO Input Length Timeouts 0000000000 2 0 COMM TIMEout 1O Output Length oes a Reset Counters Last Error Figure 21 Device tab showing firmware update utility controls If you have the S1 servo control option then you will be able to access the relevant controls on the PID sub tab of the data tab Here you can control the precision DAC output vol
50. ardware modification in the 100AB version provides this feature The feedback capacitor selection is altered to be as follows Capacitor selection Input A Input B Small 10 pF 10 pF 10 pF Large 1000 pF 10 pF 1000 pF Note that the unit operates normally when the small capacitor is selected When the large capacitor is selected however only channel B changes to the larger capacitor The result is that channel A now has one hundred times higher sensitivity and correspondingly lower full scale current than channel B for any setting of integration time The 1200 firmware needs to be aware that the hardware operates this way Any version of FPGA code 9 1 11 or later and PIC device code 4 0C or later can support the 100AB option A jumper setting on the I200 circuit board enables the correct firmware features Jumpers are fitted on positions 5 and 6 CAUTION Do not set these jumpers for standard I200 units or you will get incorrect readings 1200 User Manual Il200 UM 110905 Page 109 of 119 PSI System Controls and Diagnostics o pa G31 S3INAS 0p Eze 6e006f Old Qz ao ied ut yn Oss mor a KS 2eeegeae ies S OT Figure 61 Internal jumper Er for the 100AB option 1200 User Manual 9 HON NX amp M E a lt ra L 1200 UM 110905 gt rma tf 9 De o Page 110 of 119 PSI System Controls and Diagnostics 24 Fault fin
51. ators used in synchrotron light source beamlines The I200 has design features which make it tolerant of electrically noisy environments but the place of use is otherwise assumed to be clean and sheltered for example a laboratory or light industrial environment The unit may be used stand alone or networked with other devices and integrated into a larger system Users are assumed to be experienced in the general use of precision electronic circuits for sensitive measurements and to be aware of the dangers that can arise in high voltage circuits 1200 User Manual 1200 UM 110905 Page 15 of 119 PSI System Controls and Diagnostics 7 2 Key Features Highly sensitive charge and current measuring system Two parallel gated integrator channels External gate input Multiple data acquisition modes continuous current measurement continuous charge integration no lost charge integration externally triggered Dynamic range 0 1pA to 100uA with standard capacitors Built in calibration check current sources feeding each channel RS 232 USB and fast fiber optic serial interfaces built in Selectable baud rates Can be operated in a fiber optic serial communication loop with up to thirteen other devices 100BaseT Ethernet available through the A300 and A500 interfaces ASCII and binary serial data formats Auxiliary HV output option up to or 1000 VDC Servo control option Process parameter can be various arithmeti
52. be a noticeable fraction of the overall time Why would you choose any particular integration time The first consideration is the size of current you expect to measure For a given charge integrating capacitor the longer the integration the smaller is the maximum current you can measure and the more sensitive the I200 is to very small currents The next consideration is timing If the current you are measuring is only present in a short pulse there is little point in integrating longer than this because you will simply be measuring extra noise If the current is continuous but has variations that you wish to measure then you must have integrations short enough to be sensitive to the variations rather than smoothing them out The final consideration is filtering A given integration time used repeatedly to measure a continuous current acts as rectangular low pass filter This has the property of completely suppressing frequencies in the signal which correspond to the integration period If you are troubled by 60 Hz noise for example then using an integration period of 1 60 seconds will eliminate the problem So will any integer multiple of that period A good choice is 100 msec as this is five times the 50 Hz period and six times the 60 Hz period The I200 provides a lot of flexibility in how measurements are made Let s look at some of the parameters 9 2 Current ranges You can control the tradeoff between sensitivity to small cur
53. ber of steps and integration time to get a good measurement of the output beam intensity as a function of the DAC output voltage Assuming the DCM is positioned so that the required peak is within the piezo range the response will show a well defined peak A simulated example is shown in figure 52 8 00E 09 7 00E 09 6 00E 09 5 00E 09 4 00E 09 3 00E 09 Process value 2 00E 09 1 00E 09 0 00E 00 Control V Figure 52 Simulated system response function The general experimental requirement is for a stable and high beam flux If an operating point is defined on the side of the peak towards the top then a good compromise can be achieved where there is scope for the servo to move up or down the peak to stabilize the current but not too much flux has been given up relative to the peak Move the DAC to the required operating point by direct command and note that the expected current is being measured This current value the process variable value is the one that will become the servo target once the servo is enabled 1200 User Manual l200 UM 110905 Page 103 of 119 PSI System Controls and Diagnostics 8 00E 09 7 00E 09 6 00E 09 5 00E 09 38 4 00E 09 3 00E 09 Process value 2 00E 09 1 00E 09 0 00E 00 o ine 4 6 8 Control V Figure 53 Example operating point selection Blue user selected DAC setting orange corresponding measured current that will be used as the servo
54. by an ADC analog to digital converter The resulting binary values are converted to current readings in amps by applying calibration factors These currents can be requested over the communication link and are also used to drive the monitor outputs Let s start by looking at the measurement process in a little more detail 9 1 Current measurement process Imagine there is a small current that you wish to measure which may be varying in time as shown on the following graph Current Time Figure 4 1200 integration an example current to be measured 1200 User Manual Il200 UM 110905 Page 21 of 119 PSI System Controls and Diagnostics A conventional current to voltage conversion method would convert this current into an equivalent voltage and this voltage would be converted to a number by an ADC analog to digital converter However this method is less suitable for measuring very small currents because of signal to noise limitations The I200 therefore uses a method called gated integration instead Imagine that at some point in time zero on the graph you start accumulating integrating this current on a capacitor The capacitor will charge up and an increasing voltage will therefore appear across the capacitor Current Voltage ipo 50 0 50 100 150 200 250 300 350 400 Time Figure 5 1200 integration voltage on a capacitor that is connected at time zero If we meas
55. c combinations of the measured currents controlled parameter is a precision 0 to 10V 16 bit DAC output 1200 User Manual 1200 UM 110905 Page 16 of 119 PSI System Controls and Diagnostics 8 Specification Inputs Two independent Integration time Adjustable 20 us minimum 65 s maximum Input noise current 100 fA rms 1 fA rms per pF input load 0 1 second integration 10 pF capacitor 0 V bias Input background current lt 100 fA at 0 V bias 25 C for 8 hours after nulling lt 300 fA at 0 V bias 35 C after for 8 hours after nulling excluding external background current sources Stability Output drift 5 ppm C hour Digitization 16 bit over 10 V integrator output range Multiple conversions per integration possible sub sampling The two channels are connected to the ADC through a multiplexer Linearity Deviation from best fit line of individual readings 0 196 of maximum current or charge reading for given feedback capacitor and integration time setting Drift 0 5 over 12 hours External accuracy 0 2596 of full scale charge current for the selected capacitor and integration time Auxiliary HV PSU option 0 to 1000 V programmable 10 bit resolution ImA max Noise and ripple 0 146 of full scale External gate optical Phototransistor HFBR 1528 suitable for 650 nm External gate BNC 0 5 V TTL level 2 koh
56. conds such as might occur in a motion actuator system Noise of about 1 nA was seen with standard RG 58 but this was reduced to about 25 pA with low noise RG 58 2 00E 09 2 00E 09 1 50E 09 1 50E 09 1 00E 09 1 00E 09 5 00E 10 5 00E 10 sa 0 00E 00 ammam 9 EC 0 00E 00 i 5 5 10 15 20 25 30 5 00E 10 5 00E 10 1 00E 09 1 00E 09 1 50E 09 1 50E 09 2 00E 09 2 00E 09 Figure 49 Comparison of triboelectric noise caused by flexing standard RG 58 left and low noise RG 56 right Other mitigations include keeping the signal cables short and motionless 21 4 Battery Effects Ionic contamination such as salt from fingerprints which connects to the sensitive node can give battery effects particularly in the presence of moisture which can drive unwanted currents Any insulating surfaces in contact with the sensitive node must be clean Humidity levels should 1200 User Manual l200 UM 110905 Page 98 of 119 PSI System Controls and Diagnostics be such that there is no moisture condensation Wherever possible the sensitive node should be insulated by vacuum or air 21 5 Piezoelectric Effects Ceramic and plastic insulators can release charge when under mechanical stress which may be collected on the sensitive node The effect is generally small less than 10 pA and can be avoided by eliminating stresses in cables and connections 21 6 Integration Per
57. ding Symptom Possible Cause Confirmation Solution High background current Resistive path to signal input due to missing or broken guard Disconnect input background should reduce to specification levels Ensure good guard integrity all the way to the signal source High humidity Problem varies with relative humidity Ensure there are no water absorbent insulators Reduce the humidity levels Internal contamination Background current remains high with inputs disconnected Contact your I200 supplier for advice or to organize a return for cleaning High noise levels Integration time too short for signal being measured Noise level reduces with integration period Use an appropriate integration time for the signal level RF pickup Noise varies with cable position status of neighboring equipment Check integrity of outer screens of signal cables Line voltage pickup Noise level drops sharply if integration period is 16 7 msec 60 Hz or 20 msec 50 Hz Keep 1200 and signal cables clear of unscreened high current mains voltage Use integration periods N line frequency No signal Small signal lost in noise Signal appears as integration period is increased Use longer integration time 1200 User Manual Il200 UM 110905 Page 111 of 119 PSI System Controls and Diagnostics Signal does not vary as expected
58. e S1 servo option is a highly flexible servo controller You can define a process variable as one of several arithmetic combinations of the measured currents and the I200 will maintain the process variable by adjusting the value of a control voltage output 1200 User Manual 1200 UM 110905 Page 25 of 119 PSI System Controls and Diagnostics 10 Installation 10 1 Mounting The I200 may be mounted in any orientation or may be simply placed on a level surface A fixed mounting to a secure frame is recommended in a permanent installation for best low current performance as this can be degraded by movement and vibration Four M3 clear holes are provided in the base flange on a 152 mm by 144 mm rectangular pattern see figure 2 The mounting position should allow sufficient access to connectors and cable bend radii Leave 100mm clearance at either end for mating connectors and cable radii Best performance will be achieved if the I200 is in a temperature controlled environment No forced air cooling is required but free convection should be allowed around the case 10 2 Grounding and power supply A secure connection should be made using a ring lug from the M3 ground lug to local chassis potential This is the return path for any high voltage discharge passing via the I200 24 VDC power should be provided from a suitably rated power supply with the following minimum performance Output voltage 24 0 5 VDC Outpu
59. e chip vendor FTDI Ltd and PID C58D indicating the I200 product but have a unique serial number Microsoft Windows will recognize when a device with a new combination is connected for the first time and launch the Found New Hardware wizard The selection of files installed by the Wizard is guided by information in the file PTC INF There are two types of driver for the FTDI chip used in the I200 COM and DLL It is important not to let the wizard install the COM driver which it tends to do if you take defaults The PSI Diagnostic software requires the DLL driver The wizard should be run as follows Windows XP 1 Don t let the wizard look for drivers on the internet Found New Hardware Wizard Welcome to the Found New Hardware Wizard Windows wall search for current and updated software by looking on your computer on the hardware installation CD or on the Windows Update Web site with your permission Can Windows connect to Windows Update to search for software C Yes this ime only C Yes now and every time I connecta device No notthis tme Click Next to continue 2 Select installation from a specific location 1200 User Manual I200_UM_110905 Page 41 of 119 PSI System Controls and Diagnostics Found New Hardware Wizard This wizard helps you install software for PTCI200 d i your hardware came with an installation CD or nd floppy disk insert it now What do you wantthe wizard t
60. e Diagnostic which are available for download at no charge The program runs under the Microsoft Windows operating system with the 3 5 NET framework This has to be installed before the PSI Diagnostic All new Windows PCs have NET already installed It can be downloaded from the Microsoft web site at no charge Install the PSI Diagnostic by running the PTCDiagnosticSetup msi installer and following the screen prompts Once the program has installed you can run it at once It will allow you to connect to the I200 and depending upon your interface setup multiple additional devices at the same time The Diagnostic uses the concepts of ports and loops to organize the connected devices A port is a communications channel from your PS such as a COM port a USB port or and Ethernet port Each port can be a channel to one or more loops and each loop may contain up to 15 devices 1 Inspect the unit carefully to ensure there is no evidence of shipping damage If there appears to be damage or you are in doubt contact your supplier before proceeding 2 Connect 24 V DC power but no other connections The power LED should illuminate when the power is applied and the status and link LEDs will cycle through green orange and red see section 17 4 3 It is simplest to connect the I200 directly to the PC via its RS 232 or USB ports see figures 15 and 16 Using the USB interface you must install the USB driver see section 13 If you are using R
61. ed and screened input Practical measurements have shown that triaxial cable is rarely needed for the I200 This is in contrast to the Pyramid 1400 device where it is essential because the signal inputs can be biased several hundred volts from ground It is more important to minimize triboelectric noise see below 1200 User Manual Il200 UM 110905 Page 97 of 119 PSI System Controls and Diagnostics 21 2 Temperature Offset factors are generally exacerbated by increased temperatures Temperature fluctuation can appear as variation in the reading When very small currents need to be measured the experimental arrangement should be temperature stabilized as far as possible 21 3 Triboelectric effects When there is relative movement of insulators and conductors in signal cabling free charge is released This is particularly the case for the screen of coaxial cable The resulting potential difference can drive small currents to the signal conductor across the high impedance of the insulator Additionally charge may leak in directly if there are any breaks in the insulator Special low noise cable is available with graphite lubrication bonded to the insulator to reduce charge generation and to conduct any released charge away harmlessly Belden 9010 010100 low noise RG 58 coax cable has been tested and found to be satisfactory Figure 49 shows triboelectric noise in amps caused by deliberate flexing of coaxial cable for about ten se
62. ed with the CR LF sequence If the host is not requesting data no no other bytes will be transmitted after the ACK If the I200 generates an error when executing the host command it will transmit a single BELL 0x07 as its response A computer running a terminal program will therefore beep when the I200 cannot execute a command for example due to incorrect syntax A more interactive terminal mode can be selected which modifies this behavior to make the I200 more user friendly when it is being driven from a terminal program Device addressing is performed using the special command Addressing is only necessary for devices linked by a fiber optic loop but a device is made the listener when the host sends ADDRESS For example 4 will make the device with address 4 the listener You must ensure that all devices on the same communications channel have unique addresses All subsequent commands sent without address will be listened and responded to by device 4 only The host message asks who the listener is The command can be sent as a compound message such as 3 IDN 20 2 2 Status registers The I200 implements the IEEE 488 2 status register method Each of the registers is masked by a corresponding enable register It is recommended that you set all the enable registers to all 1 s The host software should use the STB command to watch for changes to the status of the I200 and then ESR STATus OPERation C
63. egration period measured between corresponding first and last ADC readings Minimum 100 usec maximum 10 sec tsub The subsample period tsub tpe n where n is the number of subsamples Minimum 100 usec defined by the subsample number tsetup The time between the last ADC reading in an integration cycle and the closing of SW2 to reset the integrator This has to be set long enough to ensure that the last ADC readings are not affected by the closing of SW2 treset The time the integrator is held in reset This has to be set long enough to clear all the charge from the feedback capacitor tsettle The time allowed after the integrator reset for the integrator output to settle before the first zero ADC reading is taken This has to be set long enough to clear the initial noisier part of the integrator ramp assuming the best measurement precision is required 1200 User Manual 1200_UM_110905 Page 51 of 119 PSI System Controls and Diagnostics toffset The offset positive or negative as shown in figure 26 of the SW1 opening from the start of the integrator reset On the PSI Diagnostic this is called SW1 time Front width The time that SW1 is opened to disconnect the integrators from the signal inputs at the time of reset This can be beneficial to reduce the perturbation from the reset switching transient charging the cable capacitance On the PSI Diagnostic you set SW1 time Back so twia
64. ennen 60 14 9 2 Data readout and buffering in binary mode sese 61 1200 User Manual 1200 UM 110905 Page 3 of 119 PSI System Controls and Diagnostics 14 9 3 Data readout and buffering in FastMode essere rene eene emere 61 14 9 4 DPI BOT ei ce Ua a aca tei aa e el dime be emus 63 14 9 5 Triggering trigger points and measurement timing eseseeeeeeeeen ene emen 63 14 9 6 Trigger SOULCES e004 a tee ne trside iie de ere ti E eite 63 14 9 7 Illustrations of external triggers eere e ete eee eerte e aem 65 15 Calibration and background offset current correction eee ee eese eese eene ene tn sensns enses estas tatnen 68 15 1 Background offsetsi2 ob re RO Repo REO OD RR EE RISE 68 15 2 Gain Calibration RC 69 16 High Voltage Supply sssssssissssssssssssosssosssosisessssssvosssssssossvossssssssssssssssossssssodivssosssosissvissssrsssssdsssosos sosro hsbssssssros 70 16 1 Setting the Ni Gh VOUARE isdan ae ite AE ENEA tu etie etsi ti eee 70 16 2 Hish voltare optinio RERUM e ARR Men qe ee i i 71 17 _ COMMECLOTS 73 17 1 Front panel CONNECLOTS E PE ee aeh 73 17 1 1 PUA AY TO ce Asta eh a ec hese r ta ead ae A LU ee pL 73 17 1 2 SUP Al PUTS essh EE 73 17 1 3 Auxiliary HV OUCH L eens 73 17 1 4 NUTUS 74 17 1 5 Optical gate put se i eec ter Hv coins tau aes rb me d
65. er of a sequence of seven integrations Each integration includes three sub samples for a total trigger point count of 21 Data is of course gathered on each of the two channels A similar sequence could be started by a message trigger i t Gate db 2 Vit Figure 39 Example of an external start triggered measurement sequence started by a rising edge Figure 40 shows an External Start Stop trigger example The sequence starts on the rising edge as in the previous example However in this case the 200 is also sensitive to the falling edge When the gate line falls again the sequence terminates after the acquisition in progress The external signal that starts the measurement sequence can be also be sent over the communications channel as an alternative to making a hardware connection to the gate input connector 1200 User Manual I200_UM_110905 Page 65 of 119 PSI System Controls and Diagnostics o Falling edge signals the end of the acquisition sequence LE ei Open Close Integration in progress is completed x g prog p gt L Figure 40 Example of an external start stop triggered measurement sequence started by a rising edge and ended by a falling edge Figure 41 shows an External Start Hold trigger example The gate has to go high to release the first integration If the gate is low again at the end of that integration the integrators remain in ho
66. g the integration period 14 7 Charge Accumulation Modes Applications such as radiation dosimetry often require the total charge to be accumulated so that a process can be halted when a particular value is reached When charge accumulation is turned on the I200 keeps running total of the accumulated charge across all the integrations since the last initialize If sub samples have been specified these are used as interim values to be added temporarily to the accumulating total They are superseded by subsequent sub samples in the same integration period up until the final sample which is logged permanently to the total Charge added Charge added Interim charge from to accumulator to accumulator sub sample gt Charge missed during reset Figure 31 Illustration of integrator voltage at ADC sampling points during charge accumulation The reset periods are shown relatively large There are three alternative means of dealing with the charge that is missed during the integrator resets These are no correction interpolation and no lost charge 14 7 1 No reset time correction Simply ignoring the loss during the deadtime can be appropriate when the deadtime is a very small fraction of the total time For example with one second integrations and a 10pF feedback capacitor the percentage deadtime is about 0 003 of the total time which is negligible 14 7 2 Reset time interpolation The I200 assumes that the measu
67. ge supplies Rear panel showing controls and indicators SCPI Status register structure Offset current to unguarded input 1200 User Manual 1200 UM 110905 Page 7 of 119 55 56 57 59 60 61 61 62 65 66 67 68 70 76 84 96 PSI System Controls and Diagnostics Figure 47 Guarded input 97 Figure 48 Guarded and screened input 97 Figure 49 Comparison of triboelectric noise caused by flexing standard RG 58 left and low noise RG 58 right 98 Figure 50 Separation of a 5 pA signal from background integration periods 1 msec 0 1 sec and 10 sec 100 Figure 51 DCM components relevant to servo stabilization 102 Figure 52 Simulated system response function 103 Figure 53 Example operating point selection Blue user selected DAC setting orange corresponding measured current that will be used as the servo target 104 Figure 54 Limits set on control parameter DAC voltage 104 Figure 55 Example system response with no servo 106 Figure 56 System response with integral servo term 107 Figure 57 System response with excessive integral servo term 107 Figure 58 System response with integral and proportional servo terms 108 Figure 59 System response at stability limit 108 Figure 60 System response with optimized integral and proportional terms 108 Figure 61 Internal jumper setting for the 100AB option 110 1200 User Manual 1200 UM 110905 Page 8 of 119
68. ile 10 to 1000 REFerence lt ref gt Q S1 option only Set query the normalizing reference lt ref gt for the current readings fed to the servo algorithm Float 32 Typically the stored current in a beam storage ring CONFigure Query the last configure command DATa CLEar Clear all data from I200 COUnt not supported FEEd lt source gt Q Set query source data feed mask 11 data from channels 1 2 POINts points Q Set query the data buffer size limited to available data memory VALue lt index gt Read data from buffer at index Returns lt integration time chargel charge2 over range byte FETCh CHARge Fetch charge data integration period chargel charge2 over range byte CURRent Fetch current data integration period chargel charge2 over range byte DIGital Fetch digitals bitO digital in 1 bit digital in 2 bit2 reserved bit3 HV enabled bit4 external gate present PID S1 option only Fetch the running servo data 3f DAC starting V 3f DAC present V 1200 User Manual 1200_UM_110905 Page 90 of 119 PSI System Controls and Diagnostics 3f Monitor ADC V Ae Measured process value f I1 I2 Ae Target process value f I1 I2 4e Sum of TargetProcessValue ActualProcessValue Ae Following error TargetProcessValue Ac
69. ing the 500 nA internal calibration source Note that the charge accumulates during each integration but is reset for each new integration as you would expect from the operation of the integrators 6 00E 11 5 00E 11 4 00E 11 3 00E 11 2 00E 11 1 00E 11 2 o o E o 0 00E 00 0 0E 00 1 0E 04 2 0E 04 3 0E 04 4 0E 04 5 0E 04 Time s Figure 29 Readings recorded as charge Conversion to current is simply a matter of dividing by the appropriate time interval t The reported current value for any subsample or complete integration period is _ k ADC ADC i start meas t where k coulomb bit includes the stored calibration factor for that channel with the feedback capacitor in use Figure 30 shows the result of converting the data of figure 29 to current 6 00E 07 5 00E 07 4 00E 07 3 00E 07 2 00E 07 1 00E 07 0 00E 00 0 0E 00 1 0E 04 2 0E 04 3 0E 04 4 0E 04 5 0E 04 Current A Time s Figure 30 Readings recorded as current 1200 User Manual I200_UM_110905 Page 54 of 119 PSI System Controls and Diagnostics The deadtime composed of setup reset and settle time components while the integrators are being reset does not generally affect the integrity of a current measurement The only exception would be a case where a significant frequency component of the signal happened to coincide closely with the integration cycle This can be checked and avoided if necessary by alterin
70. iod and Synchronization The I200 provides considerable flexibility in setting the integration time interval and synchronizing the integration to external events The integration method is inherently good at averaging noise Very low current currents generally require the smallest available feedback capacitor and the longest practicable integration time to build up a readily measurable voltage For example a 1 pA current integration on a 10 pF feedback capacitor requires 10 seconds to develop 1 V Background offset noise is also integrated of course and cannot be distinguished from the signal This sets the ultimate detection limit The plots in figure 44 illustrate how a 5 pA signal from a small ionization chamber becomes clearly distinguishable from a reference background signal and the noise reduces as the integration period is increased from 1 msec to 100 msec to 10 000 msec 1 msec 2 0E 10 1 5E 10 1 0E 10 5 0E 11 DEI McRae eM IC Re 5 0E 11 n 0 02 m e 0 64 gus u 0 06 bru xv x 4 5E 10 Chi ion chmbr Ch2 no signal 100 msec 7 0E 12 6 0E 12 4 a amp 5 0E 12 V 4 0E 12 4 3 0E 12 4 2 0E 12 4 1 0E 12 4 0 0E 00 1 0E 12 4 2 0E 12 Ch1 ion chmbr Ch2 no signal 1200 User Manual Il200 UM 110905 Page 99 of 119 PSI System Controls and Diagnostics 10000 msec 6 0E 12 4 5 0E 12 Je tentent 4 0E 12 4 3 0E 12 4 2 0
71. is available by email from support ptcusa com Please provide the model number and serial number of your unit plus relevant details of your application 1200 User Manual l200 UM 110905 Page 116 of 119 PSI System Controls and Diagnostics 28 Disposal We hope that the I200 gives you long and reliable service The I200 is manufactured to be compliance with the European Union RoHS Directive 2002 95 EC and as such should not present any health hazard Nevertheless when your I200 has reached the end of its working life you must dispose of it in accordance with local regulations in force If you are disposing of the product in the European Union this includes compliance with the Waste Electrical and Electronic Equipment Directive WEEE 2002 96 EC Please contact Pyramid Technical Consultants Inc for instructions when you wish to dispose of the device 1200 User Manual Il200 UM 110905 Page 117 of 119 PSI System Controls and Diagnostics 29 Declaration of Conformity Declaration of Conformity Issued by Pyramid Technical Consultants Inc 1050 Waltham Street Lexington MA 02421 USA The undersigned hereby declares on behalf of Pyramid Technical Consultants Inc that the referenced product conforms to the provisions as listed Refer to the document Extension of testing and analysis to the PTC product line December 10 2007 and the 1400 Technical Construction File for detailed testing information Product 120
72. is necessary to reset the integrator periodically at a rate determined by the average input current and the size of the feedback capacitor After the defined 1200 User Manual I200_UM_110905 Page 46 of 119 PSI System Controls and Diagnostics integration period tper switch Sw2 closes to short the feedback capacitor and release the charge so zeroing the integrator ready for the next cycle The reset time needs to be sufficient to completely clear the accumulated charge through the FET on resistance and thus depends upon the size of the feedback capacitor There is also a short settle time allowed after opening Sw2 to start the integration before the start ADC reading is taken to allow transients to die away A further time associated with the reset called the setup time accounts for the fact that the ADC conversions are not generally exactly aligned with the end of the specified integration period 1200 User Manual 1200 UM 110905 Page 47 of 119 PSI System Controls and Diagnostics 14 3 1200 Circuit Overview Two identical gated integrator channels are multiplexed into a 16 bit bipolar ADC The digitized charge values are managed by a microcontroller FPGA combination which handles all measurement timing control calibration data conversion and communications to the user s host computer system Communications can be via RS 232 USB or fiber optic using ASCII protocols based upon SCPI or binary protocols RS 232 and
73. ld until the gate goes high again In this manner the external trigger signal can directly control when the integrations occur If the gate is still high when an integration ends then the next will start immediately The whole process ends either when the trigger count is reached or the host aborts the measurement 1200 User Manual l200 UM 110905 Page 66 of 119 PSI System Controls and Diagnostics i t Gate Sw2 Vif V t Figure 41 Example of an external start hold triggered measurement sequence 1200 User Manual I200_UM_110905 Page 67 of 119 PSI System Controls and Diagnostics 15 Calibration and background offset current correction Taking accurate current or charge measurements with the I200 require accurate gain factors k for each channel and consideration of the background offset current 15 1 Background offsets Consider an integration cycle as shown in figure 42 The voltage presented to the ideal ADC comprises the integrated signal Vsienal_ current the integral of any net background offset current Vbdg current and a voltage pedestal Vofrset due to amplifier offsets and the offset of the ADC itself In practice these unwanted offsets will be much smaller than the signal and may be negative or positive relative to the signal but they must nevertheless be managed correctly to get maximum accuracy at the lowest currents and charges ADC V p di M aicin
74. lity becomes evident 5 50E 09 5 00E 09 3 4 50E 09 o D 8 4 00E 09 a 3 50E 09 3 00E 09 0 10 20 30 40 50 Time Process target Process actual 60 Figure 59 System response at stability limit You should then back off the settings until any tendency for instability is eliminated 5 50E 09 5 00E 09 3 4 50E 09 o D 8 4 00E 09 a 3 50E 09 3 00E 09 0 10 20 30 40 50 Time Process target Process actual 60 Figure 60 System response with optimized integral and proportional terms 1200 User Manual Il200 UM 110905 Page 108 of 119 PSI System Controls and Diagnostics 23 The 100AB Option The I200 100AB is a special order option of the I200 which allows you to have a factor of 100 difference in sensitivity between input channels A and B This can be useful particularly in servo applications that involve a ratio of the two signals servo mode 4 As an example a double crystal monochromator application can involve one sensor monitoring at the input beam and another looking at the monochromated beam which can be hundreds of times lower intensity In order to optimize the signal to noise ratio and resolution with this large intensity ratio it can be compensated with a corresponding sensitivity ratio between the two I200 input channels An I200 with both servo options and the 100AB option is designated I200 S1 100AB A special h
75. m input impedance Measurement start modes Internal ExternalStart start signal on gate input ExternalStartStop start and stop on gate input ExternalStartHold gate input controls integrators directly Communications Fiber optic 10 Mbit sec USB 3 Mbit sec RS 232 115 kbit sec Power input 24 VDC 4 2 V 350 mA 1200 User Manual 1200_UM_110905 Page 17 of 119 PSI System Controls and Diagnostics Case Stainless steel Case protection rating The case is designed to rating IP43 protected against solid objects greater than 1mm in size protected against spraying water Weight 1 64 kg 3 6 Ib Operating environment 0 to 35 C 15 to 25 C recommended to reduce drift and offset 7096 humidity non condensing vibration lt 0 1g all axes 1 to 1000Hz Shipping and storage 10 to 50C environment 8096 humidity non condensing vibration 2 g all axes 1 to 1000 Hz Dimensions see figures 1 and 2 1200 User Manual 1200_UM_110905 Page 18 of 119 PSI System Controls and Diagnostics FIBER OPTIC TX FIBER OPTIC RX E STATUS LEDs RS 232 Optical OXmit O Status o 9 O Rev OLink Mer Ages COMMS d ADDRESS SELECTOR SELECTOR 2X SIGNAL IN BNC SHV AUXILIARY l O DCM CONTROL 9 PIN D SUB F f 1 HV ON LED A GATE IN BNC M3 GROUND 29 9 mm LUG
76. me despite message propagation delays around the loop POINts Set query the number of trigger points after an lt poin gt IINFinite INITiate before acquisition 1200 User Manual 1200 UM 110905 Page 93 of 119 PSI System Controls and Diagnostics SOURce source Q Set query the trigger source to source The options are internal external start external gated message external start stop VOLTage DAC seting Q Set query the DAC output used for the servo to DAC setting volts 0 0 to 10 0 float 1200 User Manual 1200_UM_110905 Page 94 of 119 PSI System Controls and Diagnostics 20 3 ASCII Protocol Terminal Mode SCPI is not ideal for a user trying to control the I200 from a terminal program A more interactive terminal mode can be turned on by sending the command SYSTem COMMunication TERMinal 1 After this command is executed the I200 will provide a response to every command Valid query commands will get their normal reply Other commands will generate an OK response if they were interpreted without errors or an error message if they could not be interpreted The non printing ACK and BEL characters are not sent The I200 starts in terminal mode 20 4 Binary protocol The binary protocol is optimized for deterministic loop operation and is primarily intended f
77. ment sequence recorded by the I200 is a result of a sequence of triggers The sequence is started either internally or as the result of an external event You preset all the relevant parameters such as feedback capacitor integration period number of sub samples and type and number of triggers Then initiate the measurement The measurements only starts however when a trigger is detected As an example say that you have requested ten trigger points four sub samples per integration and ExternalStart trigger mode to be triggered by a high logic level on the BNC input The initiate command primes the I200 for datas collection but it will then wait until the trigger start event is detected The status LED will be orange in this waiting state When the gate input goes high the measurement sequence will start The status LED goes to green Four trigger points occur in the first integration period from the four sub samples four in the second integration and then the requested total of ten is reached halfway through the third integration Measurements stop being recorded and the status LED turns off Note that the analog integrators continue to run even after the measurement has been completed until you send the abort or initiate commands or new parameters are sent If you set the number of trigger points to infinite measurements will continue indefinitely following the start event If you are in internal triggering mode the start event is ge
78. nating green orange Boot state waiting start command or code download 1200 User Manual 1200_UM_110905 Page 79 of 119 PSI System Controls and Diagnostics 19 Communications Interfaces The I200 is provided with three hardware communications interfaces RS 232 USB and fiber optic The RS 232 and USB interfaces are intended for simple direct connection to PCs with no other equipment necessary The fiber optic interface provides greater speed excellent noise immunity and allows multiple devices to be connected in a looped topology It requires a fiber optic adaptor or loop controller device to connect to the host computer The fiber optic interface is well suited to large systems and experiments Only one interface is in use at any time Selection of the active interface is according to the cables that are connected Cable connected Interface selected USB RS 232 None X USB X X USB X RS 232 X Fiber optic Interface speed and protocol is selected by the mode switch The fiber optic interface can run up to 10 Mbps and the RS 232 up to 115 2 kbps The USB port always runs at 3 Mbps irrespective of the mode switch position The following table summarizes the interface selection and protocol that is active for all possible connector and mode switch configurations The most common selections are shown in bold 1200 User Manual 1200_UM_110905 Page 80 of 119 PSI Sys
79. nerated internally The sequence therefore starts immediately after you send the initiate command The I200 keeps count of the number of trigger points n following the start event and this number is used to determine the time of any measurement relative to the start of the sequence t n LIN of a J a na NI LU n settie N settle rese setup sub sub where Nsu is the number of subsamples per integration The formula simply reflects the fact that you always start with a settle time followed by an integration with a number of sub samples then followed by the reset sequence 14 9 6 Trigger sources There are several potential trigger sources and modes The gate polarity ie whether rising or falling edges cause the stated responses depends on the gate polarity parameter Internal Auto run The start event is generated internally by the I200 once the initiate message is received Readings continue until the defined number of trigger points is reached or the abort message is received External Start A rising falling edge on the gate input starts a predefined acquisition sequence Readings continue until the defined number of trigger points is reached or the abort message is received 1200 User Manual 1200_UM_110905 Page 63 of 119 PSI System Controls and Diagnostics External Start Stop A rising falling edge on the gate input starts a predefined acquisition sequence Reading
80. ng figures A suitable Hyperterminal file is provided on the I200 software CD ROM Unfortunately Windows versions since Vista do not include Hyperterminal To remedy this you can either move the relevant files hypertrm dll and hypertrm exe over from a Windows XP system or use one of the various free terminal emulation programs such as PuTTY or Realterm 1200 User Manual 1200 UM 110905 Page 29 of 119 PSI System Controls and Diagnostics COM1 Properties 2 x Port Settings Bits per second 115200 bo Data bits 8 Xj Parity None iS Stop bits 1 p lt Flow control None hd Restore Defaults 1400 test Properties ConnectTo Settings Function arrow and ctrl keys actas s Terminal keys Backspace key sends C CtrkH C Del Emulation C Windows keys Ctrl H Space Ctr H VT52 Telnetterminal ID Backscroll buffer lines x Terminal Setup VT52 500 zi Play sound when connecting or disconnecting Input Translation ASCII Setup 2 x Cancel Figure 12 Hyperterminal COM port setup ASCII Setup 2 x ASCII Sending V Send line ends with line feeds Echo typed characters locally Line delay 0 milliseconds Character delay 0 milliseconds ASCII Receiving Append line feeds to incoming line ends Force incoming data to 7 bit ASCII v Wrap lines that exceed terminal width Figure 13 Hyperterminal
81. ngths 10 A cable Keep cable from moving Use low noise cable Current across 10 to 109 A Guard the sensitive node 10 A insulators from voltage Use taxia cable 1200 User Manual 1200_UM_110905 Page 100 of 119 PSI System Controls and Diagnostics sources AC interference 10 to 109 A Used screened coaxial or 107 A AC triaxial cable AC interference 10 to 109 A Use integration periods that 107 A AC are an integer multiple of the dominant noise frequency Contaminated insulators 10 A Clean insulating surfaces with 10 A solvent Use air insulation where possible Keep humidity low Piezoelectric effects 10 to 10 A Avoid mechanical stresses and Negligible vibration in the sensor and cable Resistor Johnson noise 107A None fundamental limit set by signal source resistance Temperature fluctuation 10 to 107 A Temperature stabilize the 10 to 107 A fluctuation whole measurement apparatus fluctuation Elevated temperature 10P to 10 A Reduce temperature of the 10 A whole measurement apparatus 1200 User Manual 1200_UM_110905 Page 101 of 119 PSI System Controls and Diagnostics 22 Servo Control Applications The I200 with the S1 option contains additional hardware and software to allow it to control any process that can be commanded by a 0 to 10 V analog output signal and which can be monitored through one
82. not be connected to anything at that end The outer screen should generally terminate on the grounded enclosure of the signal source If you have an I200 with triaxial connectors but wish to adapt to low noise coaxial cable then you will need an adaptor which connects through the core and outer screen but does not connect the inner triax guard A suitable adaptor is Trompeter ADBJ20 E2 PL75 10 3 3 Signal current path Figure 10 illustrates how the current you are measuring passes along the cable inner conductor to the I200 input It effectively flows between the terminals of the input amplifier to the local analog ground due to the amplifier virtual earth then out to the case of the I200 The current then returns to the current source along the outer screen of the signal cable If you need to break the continuity of the outer screen for noise suppression reasons then you must ensure there is an alternative path between the I200 and the signal source or you will see no current 1200 Guard Current Coax screen source Alternative return if outer screen is broken PUPILS MONEMUS E zn Figure 10 Path of measured current coax inputs 1200 User Manual Il200 UM 110905 Page 28 of 119 PSI System Controls and Diagnostics 11 Getting Started in ASCII Mode Before installing the I200 in its final location and if it is the first time you have used an I200 we recommend that you familiarize yourself wi
83. o do C Install the software automatically Recommended Install from a list or specific location Advanced Click Next to continue lt Back Cancel 3 Using the browse option navigate to the location of the PTC INF file on the memory key supplied with the I200 or to the appropriate directory on your computer The driver files and uninstall files should be in the same directory as PTC INF Found New Hardware Wizard Please choose your search and installation options Search forthe best driver in these locations Use the check boxes below to limit or expand the default search which includes local paths and removable media The best driver found will be installed Search removable media floppy CD ROM v Include this location in the search CADocuments and Settings John Gordon My Documents C Don tsearch will choose the driver to install Choose this option to select the device driver from a list Windows does not guarantee that the driver you choose will be the best match for your hardware Back Next gt Cancel The wizard may find other inf files which also have valid entries depending on the history of your PC Select the PTC INF file 1200 User Manual l200 UM 110905 Page 42 of 119 PSI System Controls and Diagnostics Found New Hardware Wizard Please select the best match for your hardware from the list below amp e PTC 1400 Description Version
84. oken into two bytes encoded into the low nibble 4 bits thus never having the top bit set c A nine bit binary protocol Synchronization is done with the ninth bit The first and last byte of each message have the ninth bit set and contain the address and all other bytes are unmodified binary with the ninth bit clear ASCII messaging is provided for users who wish to use existing host software systems that provide convenient support for ASCII communications All the capabilities of the I200 are available through a familiar virtual instrument model and message structure A simple terminal program such as Windows Hyperterminal is sufficient to establish communication with the device It is possible to communicate with multiple devices at different addresses on the same channel by selecting a particular address to be the listener device at any time The binary messaging is more efficient in its use of communications bandwidth It is fully deterministic with embedded addressing in the messages and immediate responses including error reports from the devices Pyramid provides software drivers and diagnostic host programs for users who wish to use binary communication protocols Eight bit binary is primarily intended for direct host to device communication for example via RS 2332 or USB links Nine bit binary is reserved for the 10 Mbit s fiber optic channel and is highly recommended for larger systems with multiple addressable devices in a loop
85. on the internal 500 nA calibration currents to each channel Type read curr lt CR gt to read this current You should see values very close to 5 0e 7 A 11 Type syst password 12345 You are now in administrator mode and able to alter some important parameters The I200 will leave administrator mode when it is reset or the power is cycled 12 If your I200 has the external high voltage bias option type conf hivo ext max 100 This establishes 100V as the maximum value that can be set on the auxiliary HV supply The value is retained indefinitely in EEPROM until you change it Ensure nothing is connected to the signal inputs nor the external HV bias output Type conf hivo ext volt 25 lt CR gt This will turn on the high voltage at 25 V and the HV on LED will illuminate 14 Type rst lt CR gt to reset the I200 Your unit is functioning correctly and is ready to be integrated into your system 15 If you wish to explore the ASCII communication capabilities of the I200 more fully refer to the commands list in section 21 You may also wish to try out the terminal mode which provides feedback from the I200 to every message you send not just query messages and is therefore more user friendly The screenshot below illustrates this An OK response is returned immediately by the I200 for every valid command If the message was a query such as read curr this is followed by the data when it becomes available 1200 U
86. or use with Pyramid Technical Consultants host software and software device drivers If you wish to develop your own host software using binary communications you should contact Pyramid Technical Consultants to discuss available device drivers and wrappers to suit your host environment The device model for the binary communications is essentially the same as for ASCII and particularly the terminal mode All host messages get an immediate response from the I200 There are a range of summary level commands that are unavailable under SCPI For example the complete contents of the data buffer can be returned with a single command 1200 User Manual 1200_UM_110905 Page 95 of 119 PSI System Controls and Diagnostics 21 Techniques for Making Low Current Measurements Measurements of currents of around 10 nA and below require some care to prevent unwanted interference that can distort the results In particular the conductor that carries the current to the I200 input the sensitive node must be carefully isolated and guarded to ensure unwanted currents cannot flow into it When an unexpectedly high background offset current is seen the first thing to do is to check again with the signal input s disconnected from the I200 This will isolate the problem to the external measurement circuit or within the I200 itself 21 1 Guarding and screening If the sensitive node is separated from a voltage source such as a power rail by an insula
87. or two small current signals The I200 S1 calculates a process variable which is one of five available arithmetic combinations of the two input signals The servo algorithm adjusts the analog output voltage in order to maintain a selected value of the process variable Although the I200 can in principle stabilize any system that meets these criteria these notes will focus on the X ray Double Crystal Monochromator intensity stabilization application The S1 option was developed initially with this application in mind 22 1 DCM stabilization A Double Crystal Monochromator DCM accepts a broad frequency spectrum of X radiation from a source such as a bending magnet or insertion device in an electron storage ring and produces a nearly monochromatic output beam by Bragg diffraction from two crystals mounted on a crystal cage The Bragg angle and thus wavelength is selected by a precision rotary bearing Fine adjustment is achieved by a micro motor system such as a piezo motor drive The X ray beam intensity can be sensed by devices such as ionization chambers or photodiodes located downstream and upstream of the DCM DCM Sensor s Sensor Crystal cage Outgoing beam oe ee gt Incoming aL we beam 0 10V posn Main cmd Piezo amplifier rotation motor control Amp feedback Figure 51 DCM components relevant to servo stabilization Under operating conditions the operating point the outpu
88. p a suitable cable See figure 5 1200 User Manual 1200_UM_110905 Page 113 of 119 PSI System Controls and Diagnostics 25 Maintenance The I200 does not require routine maintenance There is risk of contamination which may degrade performance if the case is opened There are no user serviceable parts inside A CAUTION High voltages are present inside the case Do not open the case when power is applied The I200 is fitted with a 1 1 A automatically resetting positive temperature coefficient PTC fuse in the 24 VDC input No user intervention is required if the fuse operates due to overcurrent The fuse will reset when the overcurrent condition ends 1200 User Manual 1200_UM_110905 Page 114 of 119 PSI System Controls and Diagnostics 26 Returns procedure Damaged or faulty units cannot be returned unless a Returns Material Authorization RMA number has been issued by Pyramid Technical Consultants Inc If you need to return a unit contact Pyramid Technical Consultants at support ptcusa com stating model serial number nature of fault An RMA will be issued including details of which service center to return the unit to 1200 User Manual l200 UM 110905 Page 115 of 119 PSI System Controls and Diagnostics 27 Support Manual and software driver updates are available for download from the Pyramid Technical Consultants website at www ptcusa com Technical support
89. periods and subsample periods down to 20 usec FastMode communications are in the form of raw 16 bit data The application of the calibration and translation to physical units is performed by the A500 using calibration factors uploaded from the I200 The I200 on board memory can store up to 768 readings These are guaranteed to be contiguous even at the shortest integration and subsample periods Note that there will be deadtimes for each integrator reset however If you wish to capture a single shot event with no breaks in the data then this is still possible by using multiple subsamples in a single integration which encompasses the event Up to 256 subsamples can be used per integration The full ADC resolution is effectively shared between the subsamples You must also take care that the integrator does not overrange during the event In addition to the I200 on board storage the A500 can store over 1 000 000 readings These will be contiguous if the communications between the I200 and the A500 can keep up with the data generation rate This in turn depends upon the available bandwidth on the loop that services the I200 14 8 2 Example of single shot time resolved data capture at high rate Clearly FastMode is required for the best time resolved reading capability It is particularly suited to capturing a sequence of readings across a single shot event such as a short beam pulse where an external trigger signal is available The best way to
90. quency The inherent integration is very effective in reducing noise being in effect a rectangular low pass filter with 3dB response at 0 44 t Hz and zero response at N t Hz N 1 2 3 Known 1200 User Manual Il200 UM 110905 Page 45 of 119 PSI System Controls and Diagnostics dominant noise frequencies for example line voltage interference at 50 Hz or 60 Hz can be completely suppressed by choosing tper 1 50 or 1 60 seconds or integer multiples thereof 14 2 Sub sampling Readings are available at times n t during the integration where n 1 N with N the number of sub samples requested in the integration period tper and tsub tper N This method is most effective when you have a host system that can handle higher data rates such as the A500 real time loop controller Figure 24 illustrates how a portion of the input waveform is integrated by the opening of Sw2 The plots are from the top an illustrative input current waveform the integrator gate Sw2 state the integrator output with ADC sample points shown the ADC readings ADC readings are taken for the sub samples with ADC being subtracted from each subsequent sample to produce a charge reading ee ee c Open Closed i t Sw2 V t ADC N ADC Figure 24 Data acquisition timing diagram Integration cannot proceed indefinitely because the charge amplifier output voltage cannot exceed its voltage supply rails It
91. ration starts This is because the signal is unstable just after the reset so we wait a time called the settle time before making the first conversion This time is normally set to 20 usec The settle time can be adjusted but it is a detailed parameter that doesn t usually need to be worried about We can get a running measure of the current by simply repeating the integration cycle as many times as we want Each time we can divide the measurement of charge that is the difference between the ending and starting ADC values by the time interval between them to get the current reading In the figure the blue bars indicate the readings each is the final ADC value minus the starting ADC value for that integration Current Voltage Reading AH AATA 1300 1800 Time Figure 8 1200 integration repeated integrations to sample a continuous current signal There are some points to note Firstly notice that the readings are very clearly linked to the time of their integration Because of the resets there is no influence at all from earlier integrations Next notice also that we get no information about how the current may have varied within each 1200 User Manual l200 UM 110905 Page 23 of 119 PSI System Controls and Diagnostics integration we see only the average Finally notice that we are not measuring at all during the resets If you choose the shortest available integration times the reset time might
92. red charge in the last integration period may be pro rata extended over the total cycle tint tsetup treset tsettle The charge added to the accumulator for each integration cycle is thus 1200 User Manual I200_UM_110905 Page 55 of 119 PSI System Controls and Diagnostics k ADC ADC t per t settle vant ee Ti setup reset q lnek per T l setup l reset Laine 14 7 3 Lossless accumulation technique In critical dosimetry applications it may be important to know the total accumulated charge over a period of time without making any assumption about what happened during the integrator resets The I200 can achieve this for signal sources that can be modeled as a capacitance in parallel with a very high resistance This is a good model for ionization chambers isolated electrodes that collect charged particles and photodiodes The method is to use the inherent capacitance of the sensor C to capture the charge during the integrator reset cycle then to transfer this charge onto the feedback capacitor at the start of the next integration The switching sequence is illustrated in figure 32
93. rents and ability to measure larger currents by selecting the integration time and the feedback capacitor Longer integration times improve the sensitivity to very small currents but reduce the maximum current that can be measured Similarly the small feedback capacitor should be used to measure small currents but if you need to measure higher currents use the large capacitor As examples if you need to measure currents of only a few pA you will need the small feedback capacitor and integration time in the range 100 msec to 1 sec or more If you need to measure currents up to tens of uA you will need to select the large capacitor and use integration times in the order of 100 usec 9 3 Triggering In many cases you will need to coordinate the I200 measurements with external events You can preset the I200 with all the measurement then initiate it ready to respond to a trigger signal Measurements will start as soon as the trigger arrives 1200 User Manual 1200 UM 110905 Page 24 of 119 PSI System Controls and Diagnostics 9 4 Self testing and calibration The I200 can calibrate itself on both channels and both feedback capacitors fully automatically and it stores the resulting factors so that it can provide results in physical units amps or coulombs You can also turn on the calibration current at any time and direct it to either channel to check that the device is working correctly 9 5 Servo controller The I200 with th
94. rom high voltages generated by the device will be impaired if the unit is operated without its case Only Service Personnel as defined in EN61010 1 should attempt to work on the disassembled unit and then only under specific instruction from Pyramid Technical Consultants The unit is designed to operate from 24VDC power with a maximum current requirement of 500mA A suitably rated power supply module is available as an option Users who make their own power provision should ensure that the supply cannot source more than 1000mA A safety ground must be securely connected to the ground lug on the case Some of the following symbols may be displayed on the unit and have the indicated meanings 1200 User Manual 1200 UM 110905 Page 9 of 119 PSI System Controls and Diagnostics Direct current Earth ground terminal Protective conductor terminal Frame or chassis terminal Equipotentiality Supply ON Supply OFF CAUTION RISK OF ELECTRIC SHOCK CAUTION RISK OF DANGER REFER TO MANUAL gt PPO Ot 1200 User Manual 1200 UM 110905 Page 10 of 119 PSI System Controls and Diagnostics 4 Models I200 Two channel gated integrator electrometer with 10pF and 1000pF feedback capacitors XP10 5 2 Add positive 0 to 1000 V 500 V 200 V auxiliary bias output XN10 5 2 Add negative 0 to 1000V 500 V 200 V auxiliary bias output C x y Change feedback capacitors to
95. rrange the servo is suspended The I200 continues to put out the last output until the current s recover over the low limit 22 5 Servo tuning If you are holding a position on the left hand side of a positive peak in the mode 1 process parameter case as shown in figure 53 then the servo parameters need to be positive This is because a positive error meaning the actual process value is below the target requires an increase in control value to move up the side of the peak Conversely stabilizing on the right hand side of the peak will require negative values Generally the servo parameters will be positive if the process response curve has positive slope in the region you wish to stabilize in and vice versa Be careful to set the low and high servo limits correctly If they are too tight then the servo will not be able to follow the full range of perturbations If they are too wide the servo may fall off the peak or move over the top of the peak If the response of the system to control inputs has negligible lag then you may find that only integral control is necessary If there is lag then adding proportional term will improve the response time Too much of either term will make the loop unstable and the control output will start to oscillate The following simulated example shows how tuning the loop might proceed Initially with both servo terms set to zero the system is unresponsive to changes in the process value 5
96. ry HV out SHV male To mate with standard SHV connector such as Radiall R317 005 Core high voltage 0 1000 V Outer screen shield at chassis GND 1200 User Manual 1200 UM 110905 Page 73 of 119 PSI System Controls and Diagnostics 17 1 4 TTL gate input BNC socket female for gate and trigger inputs To mate with standard signal BNC Core signal N 0 5V Outer screen shield at GND 17 1 5 Optical gate input ST socket bayonet female for gate and trigger inputs To mate with ST terminated fiber optic 17 1 6 Ground lug M3 threaded stud To mate with M3 ring lug 17 2 Rear panel connectors 17 2 1 Power input 2 1 mm threaded jack To mate with Switchcraft S761K or equivalent Center pin 24VDC ra N px Outer OV 17 2 2 USB communications USB type B female 17 2 3 RS 232 communications Six pin mini DIN socket PS 2 mouse keyboard type 4 5 6 n c Pin 3 Gnd Pin 2 Rx Pin 1 Tx 1200 User Manual 1200 UM 110905 Page 74 of 119 PSI System Controls and Diagnostics External view on connector solder side of mating plug 17 2 4 Fiber optic communications ST bayonet To mate with ST male terminated fiber optic cable Transmitter is light gray receiver id dark gray Transmitter CON o Receiver 1200 User Manual 1200 UM 110905 Page 75 of 119 PSI System Controls and Diagno
97. s The I200 uses the gated integrator method This is a particularly effective technique for measuring small amounts of electrical charge The charge accumulates on a small low leakage capacitor in the feedback loop of an operational amplifier with the result that the voltage at the amplifier output is the integral of the current that flows into the input figure 23 FET Sw2 o o Ci WIA MT pe t t Q 0 FET 1 Swi y a pos fb Figure 23 The basic gated integrator circuit Integration starts when FET switch Sw2 is opened The current into the input can be negative or positive The voltage at the output of the amplifier is sampled and digitized by an ADC Calibration with a stable accurately known test current allows variables such as the exact size of the feedback capacitor buffer amplifier gain and ADC gain to be compensated in a single gain factor At any time t after the start of the integration the accumulated charge is thus given by d meas ES k ADC E ADC iun where k is the gain factor The data can also be presented as an average current in the time interval between the readings because that interval is known accurately k ADC ADC an t meas As the integration proceeds this measure of the average current achieves increasing signal to noise ratio as more charge is accumulated and the low pass filtering roll off due to the increasing integration time moves to lower fre
98. s continue until either the programmed number of integrations is complete or the gate input falls rises again in which case the sequence terminates after the sub sample in progress Readings continue until the defined number of triggers is reached or the abort message is received External Gated no longer supported Message A special one byte message on the communication link triggers the predefined acquisition sequence Readings continue until the defined number of triggers is reached or the abort message is received This trigger mode is only supported via the RS 232 and USB ports or via the A200 loop controller It is not supported through the A500 or A300 loop controllers ExternalStartHold A rising falling level on the gate input causes the first integration of the predefined sequence Integrations continue if the gate input stays high low After the gate falling rising edge the integrations stop after the one in progress completes The I200 then waits in reset for the next high low to cause the second integration This process continues until the defined number of triggers is reached or the abort message is received In all cases you can select infinite triggers and the acquisitions will continue indefinitely until you send the abort command or reset the I200 The external and gated modes require a physical signal via the gate input BNC or the gate input fiber optic receiver They are
99. s separated by the colon character For example CONFigure GATe INTernal PERiod 1e 2 5 This command configures the internal integration gate to have a length of 10 milliseconds with five sub samples of the integrator output after 2 4 6 8 and 10 milliseconds SCPI provides for a long and short form for each command The short forms are indicated by the capitalized part of the command denotes a required argument denotes an optional argument Some commonly used commands are available from the root of the hierarchy as a shortcut as well as in their logical position in the structure For example CAPacitor 1 and CONFigure CAPacitor 1 are equivalent ways to switch in the large feedback capacitors on the four channels A number of commands are password protected to reduce the chance of changing them accidentally The commands only effective after the device has been rebooted if they have been enabled by first sending SYSTem PASS word 12345 Sending any other number as the argument of this command disables the protected commands again 20 2 3 1 ADDRESSING DEVICES SCPI does not provide specific commands for addressing multiple devices because this was handled by hardware in the original IEEE 488 1 specification The I200 provides a simple mechanism for making any device on the loop the listener The device will remain the listener until another device is selected address Make device address 1 to 15 the listener
100. ser Manual 1200 UM 110905 Page 31 of 119 PSI System Controls and Diagnostics 1400 HyperTerminal File Edit View Cal Transfer Help Dg 55 028 4 calib gain OK calib gain 3 9 1988e 01 9 5705e 01 1 0171e400 9 8722e 01 read curr OK 1 0000e 04 4 9997e 07 A 8 7620e 10 A 0 calib source 1 OK syst password 12345 OK conf hivo ext max 100 OK conf hivo ext volt 25 OK rst OK Connected 0 01 21 vT100 115200 8 N 1 PO CAPS NUM Capture Print echo Figure 14 Example Hyperterminal session terminal mode 1200 User Manual I200_UM_110905 Page 32 of 119 PSI System Controls and Diagnostics 12 Getting Started using the PSI Diagnostic Host Program The PSI Diagnostic is a stand alone program which allows you to read graph and log data from the I200 and set all the important acquisition control parameters It supports communication via any of the interfaces For some applications it may be adequate for all of your data acquisition needs 12 1 Installing the PSI Diagnostic Program Your I200 was shipped with a USB memory stick with the installation files you need We recommend that you copy the files into a directory on your host PC The software is updated regularly to add new features and the new versions are generally compatible with prior hardware and firmware versions Check the Pyramid Technical Consultants Inc web site at www ptcusa com for the latest versions of th
101. sliscuirent V p d current poe eom lt gt t t per Figure 42 An integration showing signal and noise contributions to the final output V offset 1S eliminated automatically by the operation of the I200 because the charge is measured as k ADCy ADC so the offset cancels Background current is not eliminated automatically because it is indistinguishable from signal current at any moment in time The 200 internal background current is small pA level and stable The background from the external circuit will generally be higher but depends greatly on the particular sensor or transducer Depending upon your measurement needs it may be appropriate to subtract the total background current if it is significant relative to the signal and relatively stable You should be careful of changes to the background which would render any such correction invalid however This could be due to changes in temperature or electrical noise Background nulling can be automated in the host software The background should be measured with a long integration period sufficient to get an accurate value and with no true signal present only the background current The resulting background current values ipga for each channel can 1200 User Manual Il200 UM 110905 Page 68 of 119 PSI System Controls and Diagnostics be subtracted from subsequent current readings either manually or in host software In charge measurement modes subtract iv
102. stics 18 Controls and Indicators 18 1 Front panel controls None 18 2 Rear panel controls RS 232 Optical Xmit Status hd Rev Link Input 24V 500 mA 115K 57 6K 19 2K 2 3 4 6 7 8 Figure 44 Rear panel showing controls and indicators 18 2 1 Mode switch 10 position rotary switch setting communications mode Binary protocols are used for highest data rates by the PSI Diagnostic program and other suitable host systems The fiber optic link can run up to 1OMbps the USB up to 3 Mbps and the RS 232 up to 115 2 kbps The ASCII protocol is provided for ease of connection to existing systems and simple terminal programs Setting Function 0 9 bit binary 10 Mbps 8 bit binary 3 Mbps 8 bit binary 115 2 kbps 8 bit binary 57 6 kbps 8 bit binary 19 2 kbps ASCII 3 Mbps ASCI 115 2 kbps ASCII 57 6 kbps ASCII 19 2 kbps Reserved O CO DA tA BY QW RO The switch setting works in conjunction with the connector sensor see section 19 1200 User Manual I200_UM_110905 Page 76 of 119 PSI System Controls and Diagnostics 18 2 2 Address switch 16 position rotary switch setting device address Choice of address is arbitrary but each device in a fiber optic loop system must have a unique address Setting Function 0 Reserved to loop controller 1 15 Available address settings 1200 User Manual 1200_UM_110905
103. stored gains to nominal SOURce 011 Set query internal calibration source state 0 off l on RCL Recall the gains and zero offset currents from EEPROM SAV Store the gains and zero offset currents to EEPROM CAPacitor 0l1 Set query feedback capacitor for all channels 0 small value 1 large value CONFigure ACCumulation Set query accumulate charge across gate resets mode 0111213 0 do not accumulate accumulate by interpolation 2 accumulate by no lost charge method 3 accumulate without correction for deadtime during resets CAPacitor 0l1 Set query feedback capacitor all inputs 0 small value 1 large value GATe EXTernal POLarity 011 Set query external gate polarity external trigger only 0 high active 1200 User Manual 1200 UM 110905 Page 88 of 119 PSI System Controls and Diagnostics 1 low active INTernal LOSSless 011 Set query lossless integration mode 0 off 1 on PERiod Set query integration period in seconds or enable total IAUTOscale autoscaling lt subsamp gt subsamples per period default subsamp 1 RANGe lt amps gt Set query a full scale current range by adjusting subsamp integration period for the selected capacitor lt subsamp gt subsamples per period default 1 RESET lt reset gt Set query
104. t beam intensity variation as a function of the piezo position command forms a well defined peak Many X ray experiments require that the beam intensity after the monochromator is stable despite small fluctuations in the monochromator setting or the primary beam This can be achieved by monitoring the output beam and adjusting the piezo drive to maintain intensity under servo control 1200 User Manual I200_UM_110905 Page 102 of 119 PSI System Controls and Diagnostics In the simplest sensor system a single beam intensity sensor such as an ionization chamber or photodiode senses the beam intensity downstream of the monochromator In this simplest case the process variable is simply the current reading from channel A called I1 in the PSI Diagnostic software The I200 is perfectly suited to read out an ionization chamber and can also provide high voltage to the chamber if needed The I200 5S1 option provides a high resolution analog output to program the piezo motor amplifier and an auxiliary analog input to read the motor position feedback The integrated I200 profile function allows you to program a sweep of the analog output DAC between defined limits and with a defined number of steps N 5 A current integration is made at each step so the duration of the sweep is given by tper x Nsteps Clearly it can be best to start with a coarse profile using full span fewer steps and or shorter integration before refining the range num
105. t current 500 mA minimum 1500 mA maximum Ripple and noise lt 100 mV pk pk 1 Hz to 1 MHz Line regulation 240 mV The I200 includes an internal automatically re setting PTC fuse rated at 1 1 A However the external supply should in no circumstances be rated higher than the I200 connector limit of 5 A and a maximum of 2 0 A is recommended 1200 User Manual Il200 UM 110905 Page 26 of 119 PSI System Controls and Diagnostics 10 3 Connection to signal source 10 3 1 Typical setup Figure 9 shows a typical installation in schematic form Split readout electrodes in a signal source such as an ionization chamber are connected to the two inputs via individual coaxial cables In this example an electrode is biased by the auxiliary external high voltage output A gate signal generated by a remote timing controller for example triggers the I200 to start measuring data Data is transmitted to the host computer system via one of the I200 communications ports Conductive enclosure Signal source Loe Signals ir Comms 24V in Aux bias Gate in Figure 9 Schematic 1200 installation Refer to section 20 in this manual for general guidance on making low current measurements The I200 should be located as close to the source of the signal as possible Long signal cables increase the chances of seeing unwanted signals and noise A maximum length of 3m is advised Longer cables may
106. tage sweep the DAC over a range and look at the resulting response on the current inputs and start a proportional integral servo loop to lock the current or combination of the two currents to a particular value by controlling the DAC See section 22 for full details of the servo controller function 1200 User Manual I200 UM 110905 Page 39 of 119 PSI System Controls and Diagnostics AA D00 6 Address 6 on COMI E IIZZEZZZZEZEEEZE uu ETT AS E Current PID Initiate 9 Measuring zs Triggering Profile i Abort Q Fast Mode 3 Gated l kProp 10 z kIntegral 1 0 t Triggers n Zero Low Limit 0 0 High Limit 10 0 2 Set Clar 11 12 Low i Averaging 1x Y Reference Fre 20 40 T 60 80 100 DAC V ADC V Mode jn d Following Sum 10 0000 6 1523 Error Error Lim Data Digitals ot Opto OptoB Last Error 2 26 54 PM FETCHMONITOR 200 NotConnected Figure 22 Data PID tab showing DAC output and PI servo controls 1200 User Manual I200_UM_110905 Page 40 of 119 PSI System Controls and Diagnostics 13 USB Installation 13 1 Windows XP Installation If you intend to use the USB interface you must install the appropriate drivers on your computer Each I200 is identified on USB by a vendor identification VID a product identification PID and the unit serial number All I200s have the same VID 0403 indicating the USB interfac
107. target In order to reduce the risk that the servo looses control if there are extreme perturbations you can set low and high excursion limits on the DAC output 8 00E 09 7 00E 09 6 00E 09 5 00E 09 FIN 4 00E 09 3 00E 09 Process value 2 00E 09 1 00E 09 0 00E 00 eo no Az o co Control V Figure 54 Limits set on control parameter DAC voltage 22 2 Process parameter options The I200 S1 allows selection of five possible process parameters that will be stabilized by the servo The options are various arithmetic combinations of the two input signals I1 and D 1 Il 2 I1 D 3 I D 4 n P 1200 User Manual 1200_UM_110905 Page 104 of 119 PSI System Controls and Diagnostics 5 dl 12 1 12 Modes 1 and 2 are typical for detector systems on the output side of a DCM Mode 4 allows the output flux from a DCM to be normalized to the input flux so that the servo will not respond to variations in the beam but only to variations introduced by the DCM Mode 5 allows stabilization on the signal from a one dimensional position sensor such as a split electrode ion chamber 22 3 Process parameter normalization Some servo applications may work best if you make the servo insensitive to a particular external effect For example you may require the servo to respond to mechanical drift in the DCM or other beamline components but not to the slow drop in the circ
108. tem Controls and Diagnostics Cable connected Interface Protocol selected by mode switch setting selected USB RS None 0 1 2 3 4 5 6 7 8 9 232 X USB BIN8 BIN8 BIN8 BIN8 BIN8 ASC8 ASC8 ASC8 ASC8 3M 3M 3M 3M 3M 3M 3M 3M 3M X X USB BIN8 BIN8 BIN8 BIN8 BIN8 ASC8 ASC8 ASC8 ASC8 3M 3M 3M 3M 3M 3M 3M 3M 3M X RS 232 22 BIN8 BIN8 BIN8 ASC8 ASC8 ASC8 ASC8 115k 57 6k 19 2k 115k 115k 57 6k 19 2k X Fiber BIN9 BIN8 BIN8 BIN8 BIN8 ASC8 ASC8 ASC8 ASC8 optic 10M 3M 115k 57 6k 19 2k 115k 115k 57 6k 19 2k BIN 8 8 bit nibble oriented binary BIN 9 9 bit full binary ASC 8 8 bit ASCII SCPI message format 1200 User Manual 1200_UM_110905 Page 81 of 119 PSI System Controls and Diagnostics 20 Communications protocols 20 1 Overview The I200 supports three types of communication protocol selected according to the setting of the mode switch a An eight bit ASCII protocol messages compliant with SCPI The low seven bits are used to encode the ASCII character The eighth bit is only set for synchronization when the lt ACK gt BELL CR lt LF gt and lt ESC gt characters are transmitted b An eight bit binary protocol The first and last bytes of the entire command or reply have the eighth bit set and contain the address All other bytes in the messages are br
109. terminal settings 6 Type lt CR gt to query the active listener You should get the response 4 You are communicating successfully with the I200 If you hear your computer s bell sound when you send the string the I200 did not understand it probably because there was a typing error If the I200 does not echo correctly either the terminal settings or the I200 switch settings are likely to be wrong Check them and retry until you see the characters echo correctly If you make any errors while typing use the backspace key and re type from the error 7 Type calib gain lt CR gt The characters can be upper or lower case The I200 will perform its internal calibration sequence 8 Type calib gain CR The 200 will return the gain factors for the two channels 9 Type read curr lt CR gt The I200 will do a measurement and return the integration period it used and the measured current values for two channels The current values should be close to 1200 User Manual 1200_UM_110905 Page 30 of 119 PSI System Controls and Diagnostics background The default integration period on power up is the one that gives a one microamp full scale for example 0 1 msec for a 10 pF feedback capacitor 10 msec for a 1000 pF feedback capacitor and so on If you repeat read curr lt CR gt a few times you should see the readings change due to background noise 10 Type calib source 1 CR This turns
110. th SW1 time Back SW1 time Front Figure 27 shows examples of real internal waveforms for a setup with tper 100 usec four subsamples to give tsub 25 usec treset 20 USEC tsettle 25 USEC tsetup 8 usec Note the five pairs of ADC conversions yellow trace corresponding to four subsample measurements plus the initial zero for the two channels blue and pink traces The real integrator outputs are negative going signals as shown whereas they are shown as positive going in the schematic figures elsewhere in this manual for convenience MPos 4 800us SAVE REC Action Save Image File Format TETTE EITIIIIT Select Falder Mi 25 us Lurrent Folder Is Hit Figure 27 Example measured internal waveforms The frequency at which new complete integration readings are generated is 1 Pob dd per reset settle Tod i setup The live time proportion is given by t per t hpc sp tl reset settle l aet 1200 User Manual l200 UM 110905 Page 52 of 119 PSI System Controls and Diagnostics The default reset settle and setup times for the standard and optional feedback capacitor choices are Cr tsetup treset tsettle twidth toffset 10 pF 8 usec 20 usec 25 usec 5 usec 1 usec 1000 pF 8 usec 20 usec 25 usec 5 usec 1 usec If the livetime proportion is more important than absolute accuracy and precision in your application then
111. th its operation on the bench You can check the unit powers up correctly establish communications run the internal calibration procedure and read the internal calibration current 1 Inspect the unit carefully to ensure there is no evidence of shipping damage If there appears to be damage or you are in doubt contact your supplier before proceeding 2 Connect 24 V DC power but no other connections The power LED should illuminate when the power is applied and the status and link LEDs will cycle through green orange and red see section 17 4 3 Make a connection to a PC serial port A three wire lead terminated in a six pin mini DIN male connector PS 2 mouse type and a nine pin D female is required as in the figure below Pins are shown looking at the face of the connectors When the connector is pushed home in the 1200 the optical LED should extinguish and the RS232 should illuminate Connecting to this port forces the I200 to be a listening device 6 pin mini DIN male No 9 pin D female Figure 11 RS232 connection cable from the I200 to a PC serial port DB9 4 Set the address rotary switch to position 4 address 4 and the mode rotary switch to position 6 ASCII communication 115 kbps The address value is just for the example you can choose any number from 1 to 15 5 Configure a Windows Hyperterminal session to use COMI or other available port on your PC as shown in the followi
112. tial is the starting DAC value that the I200 was putting out when the servo was enabled The sum term keeps a running total of the errors since the servo was enabled The update period for the servo calculation is user definable in the range 5 msec 200 Hz to 255 msec 3 92 Hz Note that this period is not linked to the integration frequency According to how you set these two parameters there may be a new process value for every servo iteration many more process values than are used or multiple use of the same process value 1200 User Manual 1200 UM 110905 Page 105 of 119 PSI System Controls and Diagnostics The err value either has units of current or charge modes 1 2 3 or is dimensionless modes 4 5 If you are using process parameter normalization and the units of P are also convolved In order to keep the magnitude of the servo terms similar the values that the user enters are normalized to the full scale current for modes 1 2 3 Actual values will depend greatly upon the application but should be in the range 0 to about 100 If the DAC value reaches the lower or upper user defined by the user the servo calculation is suspended except in that any err values that would tend to move the control value off the limit are added to the sum This allows the servo to move back from the limit automatically if the error terms permit If the user defined low limit for I1 I2 is reached or if either of the inputs goes ove
113. ting layer then a small current will flow through the finite impedance of the insulator V Voltage source oo J l I Insulator Figure 46 Offset current to unguarded input For example a 10 V conductor separated from the sensitive node by 1 Gohm of total resistance would drive in 10 pA of background current If the insulation is compromised by contamination then the problem is magnified The solution is to provide a guard shield around the sensitive node at the same electrical potential in a triaxial configuration Leakages currents across insulators now flow to the guard where they do not affect the reading 1200 User Manual I200_UM_110905 Page 96 of 119 PSI System Controls and Diagnostics V Voltage source l OL D insulator Figure 47 Guarded input AC fields in the environment can induce AC currents in the sensitive node Depending upon the frequencies and the integration time in use these may appear as noise fluctuation in the signal An outer cable screen is used to shield the sensitive node from external fields In combination with the need to guard the sensitive node the result is that the use of triaxial cable is necessary in this case warn FA vA Screen Guard Figure 48 Guard
114. tualProcessValue d Error state 0x01 if DAC limit hit 0x02 if data invalid or current low limit hit PROFile S1 option only Fetch the next profile data point if not available DataNotAvailable error is returned Ae Measured process value f I1 I2 4f Monitor ADC voltage FETCh Do same FETCh command as previous defaults to charge if no previous INITiate Initiate readings on valid trigger PERiod lt period gt sub 2 Set query integration period period in seconds le 4 to 6 5el sub subsamples default is 1 PID SERVo 011 Q S1 option only Set query servo state 0 disable 1 enable PROFile 011 Q S1 option only Set query automatic profile state 0 disable 1 enable The profile will remain ON until either turned off by this command or when all data points have been read and the profile is completed READ CHARge Read charge data Returns lt integration time chargel charge2 over range flags CURRent Read current data Returns integration time current current2 over range flags gt DIGital Read digitals bitO digital in 1 bit digital in 2 1200 User Manual 1200_UM_110905 Page 91 of 119 PSI System Controls and Diagnostics bit2 reserved bit3 HV enabled bit4 external gate present PID S1 option only Read the running servo data 3f
115. ulating current in the storage ring In modes 1 2 and 3 the servo would attempt to compensate the resulting drop in flux and would probably run out of control range at some stage The I200 S1 allows this external parameter P to be removed from the servo response by normalizing the two current readings before they are passed to the calculation I1 becomes I1 P I2 becomes I2 P Thus if the measured currents on the I200 inputs are directly proportional to P any change due to variation in P is cancelled The I200 S1 cannot measure P directly but you can pass it a value that has been measured by other means via the communication link This can be done at any time including while the servo is running In between updates to the value of P the servo will be responding to its effect on the readings but by using a suitable rate of updates you can remove effect of its longer term drift Note that the value of P is irrelevant in servo modes 4 and 5 as it simply cancels out Process parameter normalization is included in firmware release 4 0E and later 22 4 Servo algorithm The I200 implements a PI proportional integral servo in firmware New values for the control voltage DAC output are given by DAC DAC initial Ker op err K integral err where err is the difference between the target process value measured at the time the servo was enabled and the latest measured value Kkprop and kintegral are the servo terms DACyni
116. ure this voltage with an ADC we will know the charge on the capacitor at the time of the conversion If we measure the voltage at two defined times we will know the increase in charge over a known time interval Current Voltage 100 50 0 50 100 150 200 250 300 350 400 Time Figure 6 1200 integration capturing the voltage at two times From this we know the average current during that time interval because average current is simply charge divided by time The time interval is called the integration period We cannot allow the voltage on the capacitor to simply increase for ever The ADC has a specified input voltage range and there is little point in exceeding it Therefore we must 1200 User Manual Il200 UM 110905 Page 22 of 119 PSI System Controls and Diagnostics discharge the capacitor periodically and this takes some time typically 20 usec Then we can restart the cycle Current Voltage po 50 0 50 100 150 200 250 300 350 400 Time Figure 7 1200 integration discharging the integration capacitor and starting a new cycle The process of charging the capacitor and discharging to reset is called gated integration The length of the integration can be controlled in the I200 in the range 20 usec up to 10 seconds and typical working values are in the range 100 usec to 1 sec Notice that the first ADC conversion does not take place immediately when the integ
117. urement process xai s eee RR S PR ee OSA edel red 21 9 2 CUPFENE TANE eS anionini e ents c BI ERE eat spony ease ERE Rie t vase t e std ete Adee 24 9 3 JTriggering cucumber OR Ue ee t te id 24 9 4 Self testing and calibrationz eee oet ae eie e eed 25 PRESA ETHIC L E UR 25 10 ptala ionannais arns aN ONEA EENEN 26 10 1 MOUNTING EE 26 1200 User Manual Il200 UM 110905 Page 2 of 119 PSI System Controls and Diagnostics 10 2 Grounding and power Supply 5i decet yat et e emite vere mthi e ede 26 10 3 Connection to Signal SOWrC soc oai e RE RE HO a UE e e ge 27 10 3 1 Typical Stu pss veces ut e eet qe e Pere e e eer ello Pee e ede ete e eee 27 10 3 2 signal cables eee Pope Render uu noD Ra adean 27 10 3 3 Signal current path oe e e te ERR THREE RR e HD suas sondeuesseouarescouveney 28 11 Getting Started in ASCII Mode eerte eese eese eee eene eene tasas etas tns tasse tosta setas etas eas eae senes ease tastes setas taae 29 12 Getting Started using the PSI Diagnostic Host Program eee esee esee eene enses etna tns tn senatus es ese tnsneno 33 12 1 Installing the PSI Diagnostic Program eese eee eene nennen nennen ai enne 33 HS USB instalation 2 5 3er eerie haee hetae tete nee cea etes se ive e Ra Te e ne o IER ENEA eiii esae ses e meece bebe ed exec du sesa 41 13 1 Windows XP Installation rnit ete tese o e tertio eh eee EN oe ut E ET a ah 4I 1
118. your system Capacitor FS range C FS range FS range A FS range A tper 100 psec tper 10 msec tper 1 sec 10 pF le 10 l uA 10 nA 100 pA 1000 pF le 8 100 uA l uA 10 nA In addition to the charges readings in coulombs and integration period in seconds the returned data also includes a bitwise overrange byte that flags any channels where the reading has gone overrange ADC value greater than 95 of full scale The lower two bits indicate overrange for channel A and channel B LSB Input A overrange Input B overrange MSB In general you should check the maximum current that you can measure for a given set of conditions if it is very important that you never overrange and provide some margin as needed 1200 User Manual 1200 UM 110905 Page 50 of 119 PSI System Controls and Diagnostics 14 5 Integrator Control The I200 allows the user a high degree of control over the integration cycle so you can optimize the operation of the device for your application The various times that can be programmed are shown schematically in figure 20 The pairs of ADC read pulses correspond to the capture of the two input channels They are about 5 psec apart Integrator output ADC conversions SW2 it t t t i reset settle sub setup SW1 t i twidth offset lt Figure 26 Programmable times for the integrator reset process tper The total int

Dual Current Integrator with Servo Control Option User Manual

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