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User`s Manual PDF

1. Model TH1912 uses the factory default settings for the power on settings Since the basic measurement procedures in this manual assume the factory defaults reset the instrument to the factory settings when following step by step procedures Table 2 1 lists the factory default settings 12 TH1912 Operation manual Table 2 1 Factory Default Settings Setting Factory Default Function DCV Range AUTO Rate Medium Remote Local Local Trigger Mode Immediate Relative Mode OFF Compare Mode OFF HI Limit 1 Lo Limit 1 Percent Mode OFF Reference 1 Max Min Mode OFF Reading Hold OFF Secondary Display Mode OFF Cal Mode OFF 2 4 6 Warm up time Model TH1912 is ready for use as soon as the power up sequence has completed However to achieve rated accuracy and stability allow the instrument to warm up for half an hour If the instrument has been subjected to extreme temperatures allow additional time for internal temperatures to stabilize 2 5Display The display of Model TH1912 is primarily used to display readings along with the units and type of measurement Annunciators located on the left right and bottom indicate various states of operation See section 2 2 1 for a complete listing of annunciators 13 TH1912 Operation manual Chapter 3 Basic Measurements 3 1 Preparation One of the first things you would like to do with your Milivoltmeter is to become acquainted with its front panel We have provided so
2. For example RESistance NPLCycle lt n gt NPLCycles To restart commands from the highest level a semicolon must be used as the separator and then a leading colon which shows that the restarted command is a command at the top of the command tree must follow For example RESistance NPLCycle lt n gt RESistance NPLCycles The common commands can restart only after a semicolon on a multiple command line For example RESistance NPLCycles lt n gt IDN 6 2 5 Command Path Rules Each new program message must begin with the root command unless it is optional e g FUNCtion If the root is optional simply treat a command word on the next 34 TH1912 Operation manual level as the root The colon at the beginning of a program message is optional and need not be used Example DISPlay ENABle lt b gt DISPlay ENABle lt b gt When the path pointer detects a colon it moves down to the next command level When the path pointer detects a colon after a semicolon it resets back to the root level The path pointer can only move down It cannot be moved up a level Executing a command at a higher level requires that you start over at the root command 35 TH1912 Operation manual Command Reference Model TH1912 provides following subsystem commands DISPlay FUNCtion VOLTage CURRent RESIstance FREQuency PERiod HOLD TRIGer FETCh Model TH1912 supports following common comma
3. PARTICULAR USE THE REMEDIES PROVIDED HEREIN ARE BUYER S SOLE AND EXCLUSIVE REMEDIES NEITHER TONGHUI ELECTRONICS NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT INDIRECT SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS INSTRUMENTS AND SOFTWARE EVEN IF TONGHUI ELECTRONICS HAS BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF SUCH TH1912 Operation manual DAMAGES SUCH EXCLUDED DAMAGES SHALL INCLUDE BUT ARE NOT LIMITED TO COSTS OF REMOVAL AND INSTALLATION LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON OR DAMAGE TO PROPERTY TH1912 Operation manual Chapter 2 Model TH1912 Digital Miullivoltmeter introduction 2 1 Introduction Model TH1912 4 Digital AC Millivoltmeter is a kind of fast and accurate AC voltage test instrument Compact front panel design can help you get the required test function quickly its inherent test platform and system feature can provide an ideal resolution for your voltage test demand now and the future Convenient test platform feature High brightness VFD Dual display Built in math operation function Get signal power of different impedance and dBm relative value Reading hold function by manual setting Convenient outline design Flexible system feature RS 232 interface Standard program language SCPI Reading rate 25 reading s COMP compare test with HI IN LO signal 2 2 Introduction of front panel The front panel of the TH1912 is sho
4. ax 8 show serial recive ready initialize the serial port void port_init int port unsigned char code union REGS r r x dx port serial port r h ah 0 intl4 function0O initial serial port r h al code initialization code int86 0x14 amp r amp r 51
5. or MEASure command is sent 6 3 7 Common Commands Common commands can be used to all equipments We provide some common commands as below RST Command Syntax RST Description Reset the instrument 44 TH1912 Operation manual TRG Command Syntax TRG Description Trigger the instrument for measurement IDN Query Syntax IDN Query return lt product gt lt version gt lt LFSEND gt Here lt product gt TH1912 A Digital AC Milivoltmeter lt version gt Ver1 0 Description Query information returned to instrument 45 TH1912 Operation manual Appendix A Specification Introduction Appendix A describes the complete specifications of the Model TH1912 Millivoltemter Technical Specifications Specifications Assumptions One year calibration cycle Operating temperature at 18 C to 28 C Accuracy is expressed as of reading digits after 30 minutes warm up Temperature Coefficient add 0 1 x the applicable accuracy C for 0 C to 18 C and 28 C to 40 C H Relative Humidity Up to 80 for 0 C to 28 C Up to 70 for 28 C to 40 C e Displayed reading and reading rate Full scale reading Slow Med Fast 38000 38000 3800 e Frequency response error of test voltage f 1KHz 5Hz 20Hz reading4 full range0 5 e gt 20Hz 2MHz reading 2 full range0 5 e gt 2MHz 3MHZ reading 3 full range0 5 e gt 3MHz 5MHZ reading 4 full ra
6. please contact your local representative or call directly to our application engineers for further consultation 1 1 Discription Model TH1912 5Hz 3MHz and TH1912A 5Hz 5MHZz are 4 Dual VFD display Dual channel AC Millivoltmeter which can also be used as power meter and level meter The test value and operation value can be displayed The operation of intelligent mico processor control technology good amplifier and A Dlinearity cymoscope make the deviation of test voltage lower than 1 Chip production and installing craft make the millivoltemeter with the good performance of small volume light high stability fast test speed small deviation of frequency reponse etc TH1912 A has wide test range 4 dual reading bright VFD display Voltage range 50uV 300Vrms 500V peak value Power level 83 8dBm 51 76dBm O0dBm 1mW 600Qload Power 0 00417nW 150W load resistance R 600Q load resistance can be set Voltage level dBV range 86dBV 49 54dBV OdBv 1V Voltage level dBmV range 26dBmV 109 5dBmV O0dBmV 1mV Voltage level dBuV range 34dBuV 169 54dBuV OdBuVv 1 pV Input resistance 1MQ parallel capacitance is about 30pF Voltage test probe when x10 input resistance is 10MQ test accuracy can t be guaranteed Max Mim recording function and percent menu function setting calculation Multi function can combine dual digit VFD display Source impedance setting test power of different signal
7. FUNCtion Command FUNCtion lt name gt Command syntax FUNCtion lt name gt Command Parameter lt name gt VOLTage AC Select AC Voltage VOLTage DC Select DC Voltage CURRent AC Select AC Current CURRent DC Select DC Current RESistance Select 2 wire Resistance FRESistance Select 4 wire Resistance FREQuency Select Frequency PERiod Select Period DIODe Select Diode Testing CONTinuity Select Continuity Testing Query FUNCtion Query currently programmed function Description This command is used to select the measurement function of the instrument Note that the parameter names are enclosed in single quotes However double quotes can instead be used For example FUNC VOLT FUNC VOLT Each measurement function remembers its own unique setup configuration such as range speed filter and rel This eliminates the need to re program setup conditions every time you switch from one function to another 6 3 3 VOLTage subsystem The commands in this subsystem are used to configure and control voltage measurement function and are summarized in Table 6 3 Table 6 3 VOLTage Subsystem Commands Summary 37 TH1912 Operation manual Command Function Description Default VOLTage DC Path to configure DC voltage NPLCycles lt n gt Set integration rate line cycle 0 5 to 2 1 NPLCycles Query line cycle integration rat
8. also be performed 1 Press LP to load 4 dB REF command in B MATH MENU press LE key to enter parameter setting REF 0 00000 2 Use L and LP to select the digits then use LA and LE to increase or decrease the value input a demanded value 3 Press to confirm the set reference voltage value Note 1 In calculating dB say V n Vrer absolute value 2 The Max negtive dB value is 160dB when Vn 1 V Meer 1000V 2 TH1912 dual channel dB operation function TH1912 has the function of channel dB operation which can perform dB operation on signal test value of dual channels The method is Press dB key to open channel dB now the flashing channel indicates reference value use LA and LE to change reference channel Press to confirm the selected reference channel the primary display is dB value Use LA and LE to select CH1 CH2 or CH2 CH1 If selecting a same channel to perform dB now Meer is the test value of reference channel when pressing Lg Press LA and LE can display reference voltage value 3 4 3 dBm calculation dBm is defined as decibels above or below a 1mW reference With user programmable reference impedance Model TH1912 A reads O0dBm when the 17 TH1912 Operation manual voltage needed to dissipate 1mW through the reference impedance is applied The relationship between dBm reference impedance and the voltage is defined by the following equation 2 dBm 10 log D Zeer Where Vis the D
9. configured for the same baud rate Perform the following steps to select a baud rate 1 Press to load Menu then use 4 or P to find c SYS MEU and press CY to enter Command use 4 or CP to find 2 BAUD RAT command press CY to enter baud rate parameter you will see BAUD lt rate gt 2 Use 4 or P to select the required baud rate then press to confirm 3 Press Shit _ key to exit from the menu and return to the measurement status 4 Software Protocol Since the hardware handshaking lines CTS and RTS are not used by TH1912 the millivoltmeter uses the character return method to decrease the data losses and errors during communication Please refer to the content below before programming communication software 1 For command syntax and format refer to Chapter 6 Command Reference 28 TH1912 Operation manual 2 The controller transmits the command using the ASCII code with lt LF gt or lt CR gt as the terminal character TH1912 executes the command after the terminal character is received 3 The character received by TH1912 will be sent back to the controller again The controller will not send the next character until the last returned character is received correctly from TH1912 If the controller fails to receive the character sent back from TH1912 the possible reasons are listed as follows The serial interface is not connected correctly Check if the same baud rate is selected for both
10. display shows the value you want as the relative value The REL annunciator turns on Press a second time to disable REL 20 TH1912 Operation manual 4 1 3 Rate The RATE operation sets the integration time of the A D converter the period of time the input signal is measured The integration time affects the usable digits the amount of reading noise as well as the ultimate reading rate of the instrument In general the fastest integration time FAST set from the front panel or remote interface results in increased reading noise and fewer usable digits while the slowest integration time provides the best common mode and normal mode rejection In between settings are a compromise between speed and noise The RATE parameters are explained as follows Fast FAST sets speed to 25 readings per second Use FAST if speed is of primary importance however it is at the expense of increased reading noise and fewer usable digits Medium Medium sets speed to 10 readings per second Use Medium when a compromise between noise performance and speed is acceptable Slow Slow sets speed to 5 readings per second SLOW provides better noise performance at the expense of speed Note The integration time can be set for any measurement function except frequency period continuity FAST and diode test Medium For frequency and period this value is little excess a gate time 4 2 Trigger operation The millivoltimeter s triggering system allow
11. instrument automatically chooses the best range to measure the applied signal However auto ranging should not be used when optimum speed is required Note that up ranging occurs at 105 of normal range and down ranging occurs at 5 of normal range To cancel auto ranging press zl or CA or CV key Pressing to cancel auto ranging leaves the instrument on the present range 4 1 2 Relative The relative operation could be used to null offsets or subtract a baseline reading from present and future readings When relative function is enabled Model TH1912 uses the present reading as a relative value Subsequent readings will be the difference between the actual input value and the relative value You can define a relative value for each function Once a relative value is set for a measurement function the value is the same for all ranges For example if 2V is setas a relative value on the 20V range the relative is also 2V on the 1000V 100V 1V or 100mV ranges Additionally when you perform a zero correction for DCV Q measurements by enabling REL the displayed offset becomes the reference value Subtracting the offset from the actual input zeroes the display as follows Displayed reading Actual Input Reference Note as for some range REL function won increase the Max allowing input signal for example in 3 8V range for the input signal higher than 3 9V TH1912 still display OVL D To set a REL value press when the
12. menu tree from one class to the next one use L or P to view the same class option of any classes Turn on menu press Menu key Turn off menu press Menu or any function key or math function key Confirm a menu command press Enter key Note TH1912 is set singlely in each channel the default setting is the channel selected by primary display Or in Parameter class press LA or LE to switch setting channel When in MENU class if you press La you can t be back to a higher menu and in Parameter if press CY 3 lower menu can t be available 2 3 Introduction of rear panel The rear panel of TH1912 is shown as Figure 2 2 this section includes many importance information before operation TH1912 Operation manual 1 RS 232 Used for RS 232 interface operation DB 9 cable must be used 2 Ground The ground terminal of instrument 3 Power jack The input terminal of AC power which can be used for AC voltage 110V 220V 10 50Hz2 60HzZ 5 4 Fuse Used for protecting instrument 220V 0 5A 5 Power input converted switch Used for switching AC 110V and 220V input The default is AC 220V 6 Platename Record the No of instrument 2 4 Starting up preparation and status 2 4 1 Power Line Connection Follow the procedure below to connect the TH1912 A to line power and turn on the instrument 1 Check to make sure that the line voltage is in the range of 198V to 242V or 110V 10 and line
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14. shipped from the factory Use the following steps to change the beeper s state 24 TH1912 Operation manual 1 Press to load Menu then use CL or P to find c sYs MEU and press CY to enter Command use L or P to find 1 BEEP command press CY to enter parameter setting 2 Use LA or LP to select ON or OFF then press to confirm 4 5 2 Key Sound To avoid mis operation Model TH1912 A has key sound function and you can enable or disable it Factory default setting is enabled The key sound state is stored in non volatile memory and does not change when power has been off of after a reset Use following steps for key sound setting 1 PressGhift to load Menu then use 4 or P to find C SYS MENU and press CY to enter Command use L or LP to find 4 KEY SONG command press CY to enter key sound setting 2 Use 4 or P to select ON or OFF then press to confirm 4 5 3 Self test The self test is a tool of testing the instrument which can help the operator find the problem as quickly as possible TH1912 has the function of booting up self test which can prove the instrument can be operated Booting up self test is just a part of self test operation but the self test in not included in analogy circuit Please refer to the information about the use of self test in TH1912 service manual 25 TH1912 Operation manual Chapter 5 Remote Operation Besides the front panel control TH1912 support
15. source and dBm value Float and GND setting meeting different test demands Auto and manual range switch function Programming language and control interface Millivoltmeter provides SCPI programming control language providing RS 232 C control interface TH1912 Operation manual 1 2 Using condition 1 2 1 Power Power voltage 220V 10 Power frequency 50Hz 60Hz 5 Consumption lt 10VA 1 2 2 Environmental temperature and humidity Normal working temperature 0 C 40 C humidity lt 90 RH 1 3 Dimension and weight Dimension WxHxD 225mmx100mmx315mm Weight about 2 5 Kg 1 4 Safety symbols and Precautions The A symbol on the instrument indicates that user should refer to the operating instructions located in the manual before performing The A symbol on the instrument shows that high voltage may be present on the terminal s Be careful to avoid personal contact with these voltages The symbol on the instruments means earth grounding The WARNING heading used in the manual explains high voltage danger that might result in personal injury or death Always read the associated information very carefully before performing the indicated procedure The CAUTION heading in the manual reminds user that hazards could damage the instruments if not according to operating instructions Such damage may invalidate the warranty TH1912 Operation manual 1 5 Incoming Inspection The TH1912 A was carefully inspec
16. the following command uses only the first two letters of the word TCouple je If the fourth letter of the command word is a consonant retain it but drop all the letters after it Example format form If the command contains a question mark query or a non optional number included in the command word you must include it in the short form version Example delay del Command words or characters that are enclosed in brackets are optional and need not be included in the program message 33 TH1912 Operation manual 6 2 3 Basic Rules of Command Structure Letter case upper and low is ignored For example FUNC VOLT DC func volt de Func Volt Dc Spaces is used to indicate a space must not be placed before and or after the colon For example wrong FUNC VOLT DC right FUNC VOLT DC The command can be completely spelled out or in abbreviated type In the following description short form will be printed in upper case For example FUNCTION VOLTAGE DC FUNC VOLT DC The command header should be followed by a question mark to generate a query for that command For example FUNC 6 2 4Multiple Command Rules The semicolon can be used as a separator to execute multiple commands on a single line The multiple command rules are as follows Commands at the same level and in the same subsystem command group can be separated by a semicolon on a multiple command line
17. window 0 01 0 1 1 and 10 of the seed reading If the reading is within the window operation again loops back within the measurement sample block This looping continues until the specified number 2 100 consecutive readings are within the winder If one of the readings is not within the window the instrument acquires a new seed reading and the hold process continues Reading Hold When a hold reading is acquired as described in Measurement Sample an audible beep is sounded if enabled and the reading is considered a true measurement The reading is held on the display until an out of window reading occurs to restart the hold process The reading hold feature allows you to capture and hold a stable reading on the display Take steps below to enable and set reading hold function 1 Press to enable reading hold function 2 Press to load Menu then use LC or CP to find B TRIG MEU and press Y to enter command use L or LP to find 2 HOLD WIN command press CY to enter parameter selection 3 Use LC or LE to select range 0 01 0 1 1 10 then press to confirm the selected range 22 TH1912 Operation manual 4 Use P to select 3 HOLD CNT press Y to enter parameter setting Default is 5 RDGS 005 5 Use 4 and CP to choose numeric place then use A and CW to increase and decrease value Enter a value of count 6 Press to confirm set digits 2 100 4 3 MAX
18. 12 Operation manual read string from serial port void string rd char ps unsigned char c i for i 0 i lt 255 i max read 256 characters while check stat PORT amp 256 wait serial recieve ready if kbhitQ amp amp getch 27 if escape key keypress printf nE21 Serial Port Read Canceled exit 1 c read port PORT ife An break ps C pst ps 0 send a character to serial port void send port int port char c union REGS r yr xX dx port serial port r h ah 1 intl4 functionl send character r hal se character to be sent int86 0x14 Er amp r if r h ah amp 128 check ah 7 if set by int86 0x14 Kr Kr mean trans error printf nE00 Serial port send error exit 1 read a character from serial port char read port int port union REGS r 50 TH1912 Operation manual r xX dx port serial port r h ah 2 intl4 function2 read character int86 0x14 amp r amp r if r h ah amp 128 if ah 7 be set mean trans error printf nE01 Serial port read error exit 1 return rh al check the status of serial port int check stat int port union REGS r r x dx port serial port r h ah 3 intl4 function3 read status int86 0x14 amp r amp r return r X ax ax 7 show serial operation
19. 3 Chapter 3 Basic Measurements s sssessesseseeertrttetetettrtrrtttetetttrtntntstetttrtnt nentrn tenn Enne 14 gT GEET 14 3 2Measuring voltage ccc eeceececceeeceeeceeeeeeeeeeeeeeeeeeeeeeceeeceeeeeeeeeeeeeeeeeeeteeeteeeteeeteentegs 14 3 3Select secondary display c ccccccceeeeeeeeeceeceeeceeeeececeneaeeeeeeeeseeeeeeaeeeeeeeeteeeas 15 3 3 1 Ope ration accents tian e ae el a een nies 15 3 4 Math operation function ccccccceceeeceeeeeeeceeeeeeeeececeeeeeeeeeeeeseneeaeaeeeeeeeeeseeas 15 SAd e EE 16 Ee DOE Lee TTT 16 3 4 9 dBm CalCulation EE 17 Chapter 4 Measurement Options s nssssesseetntttneeretittrrtrttterttrtt tnnt tsttttnr nran tteerrt nennen 19 Measurement Confguration 19 4 1 1 El Te Aust attests eee et leat ad te N 19 4 1 2 Relative ao Bickers Hime aii ine Ae Rl He 20 AVS EE 21 TH1912 Operation manual 4 2 Trigger operaton ineeaii ereere inea aina aE EEEE AA TENAAAN oae aa eda 21 D SC WR tele e De eelere TE EN Reading felt le WEE ER 4 amp 3 MAST MIN tege geg sdeiettafedregeE eate eieiei gees a r aaa 23 4 4 Compare Operation EE 23 4 4 1 Enabling Gonsten ion atnnnke 23 4 4 2 Setting Compare Limit Values eer erre rererere rrrerersrrrrrere n 23 4 5 System Operations sssaaa A ee el ia ete es 24 4 5 4 BO CD EE 24 e E IW 25 e dE 25 Chapter 5 Remote Operation 26 5 1 RS 232 Interface Operation 26 5 1 1 RS 232 Connechon siirron ei ana arenae a eaa aa Eaa ENEDES 26 5 1 1RS 232
20. C or AC input signal Z grr iS the specified reference impedance If a relative value is in effect when dBm is selected the value is converted to dBm then REL is applied to dBm If REL is applied after dBm has been selected dBm has REL applied to it Application Press to select dBm math function the secondary display is the dBm value 1 Press JK ko load 5 dBm Zx command in B MATH MENU press LE to enter parameter setting REF 0000 2 Use L and LB_ keys to choose a numerical place and use LA and LV keys to increment or decrement the digits Enter a value from 10 to 99990 3 Press ENTER to confirm the reference impedance NOTES The reference impedance and input impedance mentioned in this chapter are totally different Input impedance is inherent in the instrument and could not be changed via foregoing methods dBm is valid for both positive and negative DC voltage The percent math operations are applied after the dBm or dB math 18 TH1912 Operation manual Chapter 4 Measurement Options This chapter provides description of the front panel features of TH1912 For those measurement options accessible only by a remote interface this chapter is organized as follows Measurement Configuration Describes Ranging Relative readings Digits of Resolution and Measurement rate Triggering operations Explains trigger sources MAX and MIN operations Records the minimum and the maximum input signals Limit opera
21. MIN Used to indicate the Max and Min value in the process of testing After opening this function the instrument starts to record the Max and Min value as well as keep refreshing It can also be used to test wavery range Use the following procedure to turn on the turn on the MAX MIN operation 1 Press to enable the MAX MIN function 2 Use L or P key to switch between MAX and MIN 3 Press key again to disable the MAX MIN function 4 4 Compare Operations Limit operations set and control the values that determine the HI IN LO status of subsequent measurements Limits can be applied to all measurement functions except continuity The limit test is performed after percent math operations Unit prefixes are applied before the limit test for example Low Limit 1 0 High Limit 1 0 A 150mV reading equals 0 15V IN You can configure the millivoltmeter to beep or not when readings are outside of the limit range 4 4 1 Enabling compare Use the following procedure to turn on the limit operation Press gt to enable or disable LIMIT TEST function 4 4 2 Setting Compare Limit Values 23 TH1912 Operation manual Use the following steps to enter high and low limit values 1 Press to load Menu then use CLO or P to find A MATH MEU and press CY to enter Command use 4 or P to find 1 HIGH LIMIT command press CY to enter parameter setting HI 1 0000n 2 Use 4 and LE to change numeric place
22. Safety Precautions To optimize safety when measuring voltage in high energy distribution circuits read and 11 TH1912 Operation manual use the directions in the following warning When making measurements in high energy circuits use test leads and accessories that meet the following requirements Test leads and accessories must be fully insulated Only use test leads that can be connected to the circuit e g alligator clips spade lugs etc for hands off measurements Do not use test leads or accessories that decrease voltage spacing This diminishes arc protection and creates a hazardous condition Use the following sequence when measuring high energy circuits 1 De energize the circuit using the regular installed connect disconnect device such as a circuit breaker main switch etc Attach the test leads to the circuit under test Use appropriate safety rated test leads for this application Set the Milivoltmeter to the proper measurement function and range Energize the circuit using the installed connect disconnect device and make measurements without disconnecting the Milivoltmeter De energize the circuit using the installed connect disconnect device Disconnect the test leads from the circuit under test WARNING The maximum common mode voltage voltage between COM and the chassis ground is 500V peak Exceeding this value may cause a breakdown in insulation creating a shock hazard 2 4 5 Power on Defaults
23. TH1912 and the controller When TH1912 is busy with executing a bus command TH1912 will not accept any character from the serial interface at the same time So the character sent by controller will be ignored In order to make sure the whole command is sent and received correctly the character without a return character should be sent again by the controller 4 TH1912 only sends information under following two conditions The first is when a character is received normally TH1912 will send the character back as a handshake The second is when a query command is received TH1912 will send the query response information 5 Once a query command is received TH1912 will send the query response information immediately even if the rest commands have not been finished So if the command includes two queries the controller should read the query responses twice One query is recommended to be included in a single command 6 A query response is sent out in ASCII codes with the preset terminal character 7 Several query responses will be sent continuously with 1ms interval The controller should be ready to receive the responses otherwise the response information will be lost 8 The controller should receive the query response terminal character Otherwise you will confuse a terminal character with a returned character At the same time the controller should receive the last returned character before receiving a query response 9 For some command
24. These command are used to control auto ranging With auto ranging enabled the instrument automatically goes to the most sensitive range to perform the measurement The auto range command RANGe AUTO is coupled to the command that manually selects the measurement range RANGe lt n gt When auto range is enabled the parameter value for RANGe lt n gt changes to the automatically selected range value Thus when auto range is disabled the instrument remains at the automatically selected range When a valid RANGe lt n gt command is sent auto ranging disables REFerence lt n gt Commands REFerence lt n gt Command syntax VOLTage AC REFerence lt n gt Specify reference for ACV VOLTage DC REFerence lt n gt Specify reference for DCV Command parameter lt n gt 757 5 to 757 5 Reference for ACV 1010 to 1010 Reference for DCV DEFault 0 All measurement functions MINimum Mininum value for specified function MAXimum Maximum value for specified function Query REFerence Query reference for relative function Descripton These commands are used to establish a reference value for the specified function When reference is enabled REFerence STATe the result will be the algebraic difference between the input signal and the reference value Reading Input signal Reference From the front panel reference is called relative REL The REFerence lt n gt command is coupled to the ACQuire command The last comman
25. User s Manual VER 1 0 MODEL 1TH1912 A 4 Digit AC MilliVoltmeter TH1912 Operation manual Contents Chapter Baies e ee EE 1 TA DISCRIPUOI TEE 1 AZOSING Condition BEE 2 V2 POW EE 2 1 2 2 Environmental temperature and humidity cece eeee eee eeee eee eee 2 LG DIMention aNd WEIGH recess na D eg ease 2 1 4 Safety symbols and PDrecautions rrer terrrtrtrrrtrererrrrn n 2 1 5 incoming Min Die TEE 3 WO WAIT ln EE 3 1 7 Limitation of Warranty 0 ccccccccceecceeeeeeceeceee cece eeeeeeccaeeceeeeeeesteeensneeeeeeeetees 3 Chapter 2 Model TH1912 Digital Millivoltmeter introduction cc ceceeeeeeeeeeeeeeeeees 5 alain E 5 2 2 Introduction of front panel sssssessseseeeeererrtretstrtetrrnrnttestetrrr tnt nnrr etet ntnn nnee eere ne 5 2 2 1 Annunciators on Gcreen 7 2 2 2 Overview of front poanel 7 2 2 3 Front panel menu reierence tnnt nttrerrr renn 8 2 2 4 Menu operation introduction 0 ccc eect eeeeeneeeeeeeeeee 9 2 3 Introduction of rear pDanel rtnn nnne rerent 9 2 4 Startinging up preparation and status neeeeeeeeeees tetetete rtrr rrer tereerer nnne neern 10 2 4 1 Power Line Connecthon 10 2 4 2 Input Temmels 11 2 4 3 Power Up Geouence tnte tettttn tnte tettrer tnne tre erete 11 2 4 4 High Energy Circuit Safety Drecautions 11 2 4 5 Power on Defaults c ccccccecceeeceeeencceeeceeeeeeeceeaeeeseeeeseeeeieaeeeeeeeesseeeas 12 2 4 6 Warm up dl 13 2 9 BEE 1
26. d sent REFerence lt n gt or ACQuire eatablishes the reference When a reference is set using the REFerence lt n gt command the REFerence Query 40 TH1912 Operation manual command returns the programmed value Conversely when a reference is set using the ACQuiry command the REFerence Query command returns the acquired reference value STATe lt b gt Command syntax VOLTage AC REFerence STATe lt b gt Control reference for ACV VOLTage DC REFerence STATe lt b gt Control reference for DCV Command parameter lt b gt Tor ON Enable reference 0 or OFF Disable reference Query STATe Query state of reference Description These commands are used to enable or disable Reference for the specified function When enabled the displayed reading will include the programmed reference value When disabled the displayed reading will not include the reference value ACQuire Command syntax VOLTage AC REFerence ACQuire Acquire reference for ACV VOLTage DC REFerence AC Quire Acquire reference for DCV Description When one of these commands is sent the measurement input signal is acquired and established as the reference value This command is typically used to zero the display For example if the instrument is displaying a 1uV offset sending this command and enabling Reference zeroes the display This command is functional only if the instrument is on the specified measurement function Sending this command while in an
27. e RANGe Path to configure measurement range UPPer lt n Select range 0 to 1010 1000 UPPer Query range AUTO lt b gt Enable or disable auto range ON AUTO Query auto range REFerence lt n gt Specify reference 1010 to 1010 0 STATe lt b gt Enable or disable reference OFF STATe Query state of reference 0 1 ACQuire Use input signal as reference REFerence Query reference value VOLTage AC Path to configure AC voltage NPLCycles lt n gt Set integration rate line cycles 0 5 to 2 1 NPLCycles Query line cycle integration rate RANGe Path to set measurement range UPPer lt n Select range 0 to 757 5 757 5 UPPer Query range AUTO lt b gt Enable or disable auto range ON AUTO Query auto range REFerence lt n gt specify reference 757 5 to 757 5 0 STATe lt b gt Enable or disable reference OFF STATe Query state of reference ACQuire Use input signal as reference REFerence Query reference value Speed Commands NPLCycles lt n gt Command Systac VOLTage AC NPLCycles lt n gt VOLTage DC NPLCycles lt n gt Command Parameter lt n gt 0 5to2 DEFault MINimum MAXimum Set NPLC for ACV Set NPLC for DCV Set power line cycles per integration TH1912 Operation manual Query NPLCycles Query programmed NPLC value Description The integration period measurement speed for the basic measurement functions except Frequency and Period is set using the NPLCycles comma
28. e value the following operation can also be performed except the description above 1 Press again to load 3 PERC REF command of A MATH MEU press CY to enter parameter setting 1 0000n 2 use 4 and LP to select the required digit then usel A and LY to add or subtract value and input a required value and unit 3 Press to confirm reference value Model TH1912 A will display measurement result of calculation If the value of Input is larger than that of Reference displayed result will be positive contrarily it will be negative if the value of Input is smaller than that of Reference 3 4 2 dB calculation Expressing DC and AC voltage in dB makes it possible to compress a large range of measurements into a much smaller scope The relationship between dB and voltage is defined by the following equation 16 TH1912 Operation manual dB 20 log SA REF Where V is the DC or AC input signal Mar is the specified voltage reference level The instrument will read OdB when the reference voltage level is applied to the input If a relative value is in effect when dB is selected the value is converted to dB then REL is applied to dB If REL is applied after dB has been selected dB has REL applied to it 1 Application Press to select dB math function dB value is displayed on secondary display After opening dB math function if you need to change reference value the following operation can
29. figure 3 Press again to turn off secondary display function and primary display can t be affected Figure 3 1 Pe Secondary display gt KR V dBm dB WwW dBV Vp p dBmV dBuV dBm dB WwW dBV Vp p dBmV dBuV V W dBV Vp p dBmV dBuV V dBm dB dB WwW dBV Vp p dBmV dBuN V dBm dBV Vp p dBmV dBuV V dBm Vp p W dBmV dBuV V dBm Vp p WwW dBV Vp p Vp p dBmV dBuV V dBm dB W dBV dBuV V dBm dB WwW dBV Vp p dBmV Percentage Jo Comp HI IN LO PASS FAIL Max Min Max Min 3 4 Math operation function There are 3 kinds of math operation in TH1912 e Percentage e dB e dBm 15 TH1912 Operation manual The procedure of selecting and setting math function is as below Press corresponding math function key to turn on the function Set the parameter of math function and press to confirm If press the math function key the math function will be cancelled 3 4 1 Percent Percent operation is based on the reference value you set Percent Hp Relea x 100 Reference Where Input General display reading on the screen Reference User inputting parameter Percent Calculated result Application The application of Percent math function please operate based on the following methods Press to select Percent math function Percent value is displayed on secondary display After opening Percent math function if you need to change referenc
30. frequency is in the range of 47 5 to 52 5Hz or 6 0Hz 5 before connecting the power cord 10 TH1912 Operation manual CAUTION Operating the instrument on an incorrect voltage may cause damage to the instrument possibly voiding the warranty 2 Before plugging in the power cord make sure that the front panel power switch is in the off position 3 Connect the female end of the supplied power cord to the AC receptacle on the rear panel Connect the other end of the power cord to a grounded AC outlet WARNING The power cord supplied with the Model TH1912 A contains a separate ground wire for use with grounded outlets When proper connections are made instrument chassis is connected to power line ground through the ground wire in the power cord Failure to use a grounded outlet may result in personal injury or death due to electric shock 4 Turn on the instrument by pressing the front panel power switch and get ready for measuring 2 4 2 Input Terminals Input terminal function is shown as Figure 2 3 Float indicator light float off ground BNC Jack 2 4 3 Power up Sequence On power up Model TH1912 performs self tests on its EPROM and RAM and lights all segments and annunciators for about 1 second If a failure is detected the instrument momentarily displays an error message and the ERR annunciator turns on If the instrument passes self tests the firmware revision will be displayed 2 4 4 High Energy Circuit
31. ge made on parameter level and return to the command level 5 Range and Combination function selecting keys ER Select a 2 display parameter gt Select a 2 display parameter LA Select a higher range and disable auto ranging Lv Select a lower range and disable auto ranging Toggle between auto ranging and manual ranging 6 Trig Hold key TH1912 Operation manual Tig Trigger a measurement from the front panel Hold a stable reading on the display 7 Shift Local key Used to access shifted keys Local Cancel RS232C remote control mode and back to the LOCAL mode 2 2 1 Annunciators on Screen FAST MED SLOW TRIG HOLD AUTO REL MATH KM DCH E ACH ACH2VN VAL WN BN VIN DN EN IN WN COMP HU MM CO RMT AUTO MAX MIN EE SHIFT FAST Fast reading rate MED Medium reading rate SLOW Slow reading rate TRIG Indicates external trigger front panel bus selected HOLD Reading HOLD function is enabled AUTO Auto ranging enabled REL Relative operation function CH1 CH2 channel indication COMP Turn on limit compare test function HI IN LO limit compare high pass pass and low pass indication RMT Milivoltmeter is in remote control mode AUTO Auto ranging enabled MAX MIN Max Min The indication of Max and Min value ERR Hardware or remote control error detected SHIFT Accessing shifted keys 2 2 2 Overview of front panel The menu of TH1912 is organized by 3 classes menu command top down tree struct
32. ial port state 16bit void send port int port char c send a character to serial port char read port int port recive a character form serial port void string wr char ps write a string to serial port void string rd char ps read a string from serial port char input 256 quary recieve bufer main port init PORT Oxe3 initilize serial port baud 9600 no verify 1 bit stop 8 bit data string wr trig sour bus trg string rd input printf n s input string wr volt dc rang 1 0 string wr func volt ac 48 TH1912 Operation manual write string to serial port void string wr char ps char c int m n while check stat PORT amp 256 read port PORT read data until null for ps e 0 for m 100 m m send port PORT ps for n 1000 n n delay 2 wait about 2ms can use dos h libray funtion delay if kbhitQ amp amp getchQ 27 if escape key keypress printf nE20 Serial Port Write Canceled exit 1 if check stat PORT amp 256 c read port PORT break if n break if c ps pst else printf nEl10 Serial Port Write Echo Error exit 1 send port PORT n send command end symbol delay 2 while check stat PORT amp 256 read port PORT 49 TH19
33. mand syntax HOLD STATe lt b gt Command Parameter lt b gt 0 or OFF 1 or ON Query STATe Disable HOLD Enable HOLD Query state of HOLD 6 3 5 TRIGger subsystem These commands in this subsystem are used to configure and control trigger measurement function and are summarized in Table below Command Function Description Default TRIGger SOURce lt name gt Select control source IMMediate SOURce Query control source TRIGger TRiGger subsystem commands are used for the instrument settings of trigger mode trigger delay and trigger a measurement SOURce lt name gt Command Syntax TRIGger SOURce lt name gt Command parameter lt name gt IMMediate BUS 43 instrument default setting is internal trigger Triggered via RS232 interface TH1912 Operation manual MANual EXTernal Press in the front panel for Trigger Query SOURce Query control source Description These are used to select the event control source 6 3 6 FETCH Subsystem FETCh Command Command syntax FETCh Description This query command is used to obtain the lastest post processed reading This command does not affect the configuration of the instrument This command does not trigger a measurement The command simply requests the last available reading This command continues to return the same old reading until there is a new reading This command will be automatically asserted when READ
34. me exercises in foregoing chapters about preparations for use and operations of front panel The front panel has six rows of keys to select various functions and operations Most keys have a shifted function printed in blue above the key To perform a shifted function press Lang the Shift annunciator will turn on Then press the key that has the desired label above it If you accidentally press H just press it again to turn off the Shift annunciator 3 2 Measuring voltage TH1912 voltage ranges 3 8 mV 38mV 380mV 3 8V 38V 300V 500V peak value highest resolution 0 1uV In 3 8mV range Connection method If TH1912 is under the setting condition the operational procedure is 1 Voltage probe BNC is connected to BNC jack when testing small voltage probe ground line should be short as possible to avoid voltage interference 2 Press to lock auto range function After booting this function be attention AUTO lights If you need manual range use A and LT to select the test range of required voltage 3 Read the reading on the display 14 TH1912 Operation manual 3 3Select secondary display At default status secondary display is displayed by 4 or P Assembled display of secondary parameter the group is listed as Figure 3 1 3 3 1 Operation 1 Press to open secondary display function 2 Press 4 or P to select the assembled group of each secondary parameter in primary display function details in shown as
35. nd NPLC Number of Power Line Cycles expresses the integration period by basing it on the power line frequency For example for a PLC of 1 the integration period in seconds would be1 60 for 60Hz line power which is 16 67 msec RANGe Commands UPPer lt n gt Command syntax VOLTage AC RANGe UPPer lt n gt Set measurement range for ACV VOLTage DC RANGe UPPer lt n gt Set measurement range for DCV Command Parameter lt n gt Oto 757 5 Expected reading is AC volts ACV 0 to 1010 Expected reading is DC volts DCV DEFault 757 5 ACV 1000 DCV MINimum 0 All functions MAXimum Same as DEFault Query RANGe UPPer Query measurement range of the current function Description This command is used to manually select the measurement range for the specified measurement function The range is selected by specifying the expected reading as an absolute value The instrument will then go to the most sensitive range that will accommodate that expected reading For example if you expect a reading of approximately 20mV simply let the parameter lt n gt 0 02 or 20e 3 in order to select the 200mV range AUTO lt b gt Command syntax VOLTage AC RANGe AUTO lt b gt Set auto range for ACV VOLTage DC RANGe AUTO lt b gt Set auto range for DCV Command parameter 39 TH1912 Operation manual lt b gt 1orON Enable auto range 0 or OFF Disable auto range Query AUTO Query auto range ON or OFF Description
36. nds RST TRG IDN 6 3 1 DISPlay subsystem The DISPlay subsystem commands are mainly used to control the display of the TH1912 A and are summarized in Table 6 1 Table 6 1 DISPlay Subsystem Commands Summary Command Function Description DISPlay ENABle lt b gt Enable or disable front panel dispaly ENABIe Query state of the display ENABle lt b gt Command syntax DISPlay ENABle lt b gt Command Parameter lt b gt Oor OFF Disable front panel display 1 or ON Enable front panel display Query ENABle Query state of the display Description This command is used to enable or disable front panel display circuitry When disabled the instrument operates at a higher speed While disabled the display is frozen All front panel controls except LOCAL are disabled Normal display operation can be resumed by using ENABle command or pressing LOCAL key to enable the display 6 3 2 FUNCtion subsystem The commands in this subsystem are used to configure the measurement function subsystems and are summarized in Table 6 2 Table 6 2 FUNCtion Subsystem Commands Summary Command Decription 36 TH1912 Operation manual FUNCtion lt name gt Select measurement function VOLTage AC VOLTage DC RESistance FRESistance CURRent AC CURRent DC FREQuency PERiod DIODe CONTinuity FUNCtion Query function
37. nge0 5 Triggering and Memory 46 TH1912 Operation manual Reading hold sensitivity 0 01 0 1 1 or 10 of reading Programming trigger delay 0 6000ms with step of 1ms Memory save 512 reading Math function Rel Max Min Average standard error stored reading dBm dB Limit Test and mX b dBm reference resistance value automatically set 10 9999Q0 with the stepper of 1Q default is 750 Standard program language SCPI Standard Commands for Programmable Instruments Remote interface GPIB IEEE 488 2 and RS 232C General specification Power requirement 220V 10 Power frequency 50 60Hz 5 Power consumption s20VA Working temperature 0 C 40 C lt 90 RH Stored environment 40 C 70 C Warming up time at least 30 minuets Dimention WxHxD 225mmx100mmx315mm Weight about 2 5 Kg Warrenty period 2 years 47 TH1912 Operation manual Appwndix B Example of program Serial interface program The example is a communication program written with C language under pure DOS environment main function can expand communication function by user and subfunction decribes how to use serial interface to input and output string define PORT 0 include dos h include stdio h include stdlib h include ctype h include string h include conio h void port_init int port unsigned char code int check stat int port read ser
38. on manual Function Code Connector Pin Number Transmitted TXD 3 Data Received Data RXD 2 Signal Ground GND 5 Common Note the definition of serial port pin is the same as that of standard 9 core RS232C connector RS 232 connector adopts 9 core DB jack the pin sequence is shown as the figure below 12345 o W s 6789 RS232 Rear panel connector 5 1 1 RS 232 operation 1 The connection of RS232 and computer is shown as figure 5 1 HFL Figure 5 1 RS 232 connection There may be some difference between TH1912 RS232 interface and a standard RS232C interface You can make the connection cable by yourself according the diagram or order one from our company Note Pin 4 and 6 pin 7 and 8 are shorted respectively at the end of controller 27 TH1912 Operation manual 2 Sending and receiving data TH1912 EH EA i 8 Ai IESSE GEORGES EEN EE OH ER Ay BPL bit BHA ir it FIE WAREM bit RALE RITT ASC TIRRI X 10 3 Selecting Baud Rate The baud rate is the rate at which Model TH1912 millivoltmeter and the computer communicate Choose one of these available rates H 38 4k 19 2k 9600 4800 2400 1200 600 Note Factory default baud rate is 9600 Before you choose a baud rate make sure the programming terminal that you are connecting to the TH1912 can support the baud rate you selected Both the millivoltmeter and the other device must be
39. peration Example CURRent AC RANGe AUTO ON Enable auto ranging lt name gt Name parameter Select a parameter name from a listed group Example lt name gt MOVing REPeat RESistance AVERage TCONtrol MOVing 32 TH1912 Operation manual lt NRf gt Numeric Representation format This parameter is a number that can be expressed as an integer e g 6 a real number e g 25 3 or an exponent e g 5 6E2 Example MME achor 5 lt n gt Numeric value A numeric value parameter can consist of a NRf number or one of the following name parameters DEFault MINimum MAXimum When DEFault parameter is used the instrument is programmed to the RST default value When the MINimum parameter is used the instrument is programmed to the lowest allowable value When the MAXimum parameter is used the instrument is programmed to the largest allowable value Examples CURRent DC NPLCycles 1 CURRent DC NPLCycles DEFault CURRent DC NPLCycles MINimum CURRent DC NPLCycles MAXimum 6 2 2 Short form Rules Use the following rules to determine the short form version of any SCPI command If the length of the command word is four letters or less no short form version exists Example AUTO AUTO These rules apply to command words that exceed four letters If the fourth letter of the command word is a vowel delete it and all the letters after it Example immediate imm Rule exception The short form version of
40. s RS 232 serial interface for remote control Standard Commands for Programmable Instruments SCPI is fully supported to communicated with computer via the RS 232 interfaces with a certain communication protocols You can connect RS 232 interface with a computer Some considerations will draw your attention m You must define the baud rate H You must use the SCPI programming language 5 1 RS 232 Interface Operation The instrument provides various remote commands All operations from the front panel can be performed by a computer via the RS 232 interface 5 1 1 RS 232 Connection RS232C standard now is widely used as the serial communication standard RS232 stands for Recommend Standard number 232 and C is the latest revision of the standard The serial ports on most instruments use a subset of the RS232C standard The full RS232C standard specifies a 25 pin D connector of which 22 pins are used Most of these pins are not needed for normal serial communications Funston on 25 Pin connector 9 Pin Connector Pin Number Pin Number Request To Send RTS 4 7 Clear To Send CTS 5 8 Data Set Ready DSR 6 6 Data Carrier Detect DCD 8 1 Data Terminal Ready DTR 20 4 Transmitted Data TXD 2 3 Received Data RXD 2 Signal Ground Common GND 5 TH1912 only uses the smallest subset of the RS232C standard the signal are listed as below 26 TH1912 Operati
41. s that will take a long time to execute for example reset command the controller should keep waiting to avoid the next command being lost when TH1912 is executing the former command 5 2 Data format TH1912 outputs the measurement results using the ASCII character string format via the RS232 serial interface The data format is described as below 29 TH1912 Operation manual SD DDDDDDESDDD lt NL gt S D number 0 to 9 E exponent sign ris omitted lt NL gt New Line ASCII code is 10 30 TH1912 Operation manual Chapter 6 SCPI Command Reference 6 1 Command structure TH1912 commands are divided into two types common commands and SCPI commands The common commands are defined in IEEE std 488 2 1987 and these commands are common for all devices Not all commands are supported by the TH1912 The SCPI commands are used to control all of the TH1912 s functions The SCPI commands are tree structured three levels deep The highest level commands are called the subsystem commands in this manual So the lower level commands are legal only when the subsystem commands have been selected A colon is used to separate the higher level commands and the lower level commands See Figure 6 1 for a sample IRESistance SENS RES RANG 1k SENS HOLD STAT ON SENS RES RANG AUTO ON Figure 6 1 Command Tree Example 6 2 Command Syntax The information in this section covers the syn
42. s you to generate triggers either manually or automatically or externally and take multiple readings per trigger The following paragraphs discuss front panel triggering and the reading hold feature 4 2 1 Trigger procedure Wait for Trigger The control source holds up operation until the programmable event occurs and is detected See description below for trigger sources E Immediate 21 TH1912 Operation manual With this trigger source event detection is immediately satisfied allowing operation to continue H External Event detection is satisfied for both kinds of triggers as below 1 Abus trigger TRG command is received 2 The front panel key is pressed TH1912 A must be taken out of remote before it will respond to key Take steps below for trigger settings 1 Press to load Menu then use L or P to find B TRIG MEU and press Y to enter Command use L or P to find 1 TRIG MODE command press Y to enter parameter IMM MAN or BUS setting 2 Use LC or P to select IMM MAN or BUS then press to confirm 3 Measurement Sample The primary measurement sample action is a measurement However the measurement sample action block could include the following additional actions Hold with hold enabled the first processed reading becomes the Seed reading and operation loops back within the measurement sample block After the next reading is processed it is checked to see if it is within the selected
43. tax for both common commands and SCPI commands 6 1 1 Commands and command parameters Common commands and SCPI commands may or may not use a parameter The following are some examples RST No parameter used 31 TH1912 Operation manual FORMat lt name gt Parameter lt name gt required IMMediate No parameter used Put at least one space between the command word and the parameter Brackets Some command words are enclosed in brackets These brackets are used to denote an optional command word that does not need to be included in the program message For example RANGe UPPer lt n gt These brackets indicate that UPPer is optional and does not have to be used Thus the above command can be sent in one of the two ways below RANGe lt n gt or RANGe UPPer lt n gt NOTICE When using optional command words in your program do not include the brackets Angel brackets lt gt Angle brackets are used to denote a parameter type Do not include the brackets in the program message For example HOLD STATe lt b gt The lt b gt indicates that a Boolean type parameter is required Thus to enable the HOLD feature you must send the command with ON or 1 parameter as below HOLD STATe ON or HOLD STATe 1 Parameter types The following are some of the more common parameter types lt b gt Boolean Used to enable or disable an instrument operation 0 or OFF disables the operation and 1 or ON enables the o
44. ted mechanically and electrically before shipment After unpacking all items from the shipping carton please check for any obvious signs of physical damage that may have occurred during transportation Report any damage to the shipping agent immediately Save the original packing carton for possible future reshipment The following items are included with every Model TH1912 A order e Model TH1912 A Alt Digital AC Milivoltmeter Test leads Model TH26036 Power cord Two 500mA fuses Two 1A fuses Operation Manual Quality and warranty certificate Test report Other optional accessories if ordered Verify that you have received all the items above when you get Milivoltmeter If anything is missing please contact our representative or our sales office 1 6 Warranty Tonghui warrants this product to be free from defects in material and workmanship for a period of 2 years from the date of shipment During the warranty period we will at our option either repair or replace any product that proves to be defective 1 7 Limitation of Warranty This warranty does not apply to defects resulting from product modification without our express written consent or misuse of any product or part This warranty also does not apply to fuses software or problems arising from normal wear or failure to follow instructions THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES EXPRESSED OR IMPLIED INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A
45. then use A and CY to increase and decrease the value Enter a value of count Press to confirm high limit value 3 Use P to select 2 LOW LIMIT press CY to enter low limit parameter setting LO 1 0000n 4 Use 4 and LE to change numeric place then use A and LY to increase and decrease the value Enter a value of count Press to confirm low limit value 5 Press gt key to exit from the menu and return to the measurement status 4 5 System Operations Model TH1912 has some other operations Beeper control key sound control Baud rate control and Terminal character setup The information is not directly related to making measurements but is an important part of operating the instrument 4 5 1 Beep Normally the millivoltmeter will emit a tone whenever certain conditions are met For example the millivoltmeter will beep when a stable reading is captured in reading hold You may want to disable the beeper for certain applications When you disable the beeper the millivoltmeter will not emit a tone when 1 A limit is exceeded in a limit test 2 A stable reading is captured in reading hold Disabling the beeper has no effect on the tone generated when 1 An internal error is generated 2 The continuity threshold is exceeded 3 Afront panel key is pressed kal The beeper state is stored in non volatile memory and does not change when power has been off or after a reset The beeper is enabled when the millivoltmeter is
46. tions Defines how to set reading limits System Operations Provides details on Beep setup Baud rate setup Terminal character setup and key sound setup up Measurement configuration The following paragraphs discuss configuring Milivoltmeter for making measurement 4 1 1 Range You can let the millivoltmeter automatically select the range using auto ranging or you can select a fixed range using manual ranging Auto ranging is convenient because the millivoltmeter automatically selects the appropriate range for each measurement However you can use manual ranging for faster measurements since the millivoltmeter doesn t have to determine which ranging to use for each measurement The millivoltmeter returns back to auto ranging when power has been off or after a remote interface reset Maximum readings The full scale readings for every range on each function are 5 over range Manual ranging To select a range simply press LA or LV key The instrument changes one range per key press The selected range is displayed for a moment If the instrument displays the OVL D message on a particular range select a higher range until an on range reading is displayed Use the lowest range possible without causing an overflow to ensure best accuracy and resolution 19 TH1912 Operation manual Auto ranging To enable auto ranging press key The AUTO annunciator turns on when auto ranging is selected While auto ranging is selected the
47. ure TH1912 Operation manual DERES COO rinra CV CA ireas l A MATH MEU gt B TRIG MEU cht C SYS MEU kor 2 COMP LO 1 TRIG MOD gt 2 HOLD WI Press to confirm A MATH MENU 1 COMP HI 2 COMP LO 3 PERC REF gt 4 dB REF gt 5 dBm REF8 B TRIGger MENU 1 TRIG MODE 2 HOLD WIN gt 3 HOLD CNT C SYStem MENU 1 BEEP STR 2 KEY SONG gt 3 BAUD RATe gt 4 Tx TERM 5 GND STA 2 2 3 Front panel menu reference A MATH MENU 1 COMP HI Set high limit for COMP 2 COMP LO Set low limit for COMP 3 PERC REF Set reference value for PERCENT 4 dB REF Load or set dB reference value saved in register 5 dBm Zx Load or set load reference value saved in register B TRIG MENU 1 TRIG MODE Select trigger mode IMM MAN BUS 2 HOLD WIN Set the reading hold sensitivity band 3 HOLD CNT COUNT of readings for reading hold C SYS MENU 1 BEEP STR Enable or disable the beeper function 2 KEY SONG Enable or disable the key sound 3 BAUD RAT Select baud rate of RS232C interface 4 TX TERM Set ending character in RS232C transmission TH1912 Operation manual 5 GND STA Set input signal ground or float 2 2 4 Menu operation introduction The section briefly introducts how to use the menu of front panel It is suggested that operator should know and hold the menu structure and operation Menu is designed by top bottom 3 classes Menus Commands Parameters tree structure You can use LA or LE to move
48. wn in Figure 1 1 This figure includes some important abbreviated information that should be reviewed before operating the instrument TH1912 Operation manual 1 UE 2 BFE e N rt DZ e a Z TH1912 4x Digit AC milivoltmeter Ic y dBm INPUT i i 30OVRMS 500V PK we auto NM i e pH SS W dB w CHI wi Im i 1 1 CHI gt SWOLIO ry L 1 V PEP dBuV 4 WW E D steet panini e e 1MQ 30pF fill che d my L r Com Ti HA A FEIE fll iC Rel Wax Min 1 300VRMS 500VPK E aer HoT T EN J Rate Trig CH2 a gt v A Ato E al IMQ I1 300 Wet Fleet H Jenu Le i S 30V RMS POWER HEJTA 5 EFM A mer 3 EA 6 Trig Hold Si BERF 7 Shift Local S 1 Function key Select test function AC voltage valid value V gt voltage peak peak value Vp p power W power level dBm voltage level dBV dBmV dBuV relative test value dB 2 Numeric key Turn on or off math function Rel Max Min Comp Hold 3 2 Display and speed key Changes reading rate Fast Medium and Slow gt turns on off the 277 parameter display 4 Menu operation keys Ese Open Close menu ER Move through selections within menu level command level or parameter level Move through selections within menu level command level or parameter level a Move up a level A Move down a level ENTER Save the change made on parameter level and return to the command level Cancel the chan
49. y other function causes an error Also if the latest reading is overflowed or a reading has not been triggered an error occurs when this command is sent 41 TH1912 Operation manual 6 3 4 HOLD subsystem The commands in this subsystem are used to configure and control hold measurement function and are summarized in Table below Command Function Description Default HOLD Path to control Hold feature WINDow lt NRf gt Set Hold window 0 01 to 10 1 WINDow Query Hold window COUNt lt NRf gt Set Hold count 2 to 100 5 COUNt Query HOLD count STATe lt NRf gt Enable or disable HOLD OFF STATe Query state of HOLD HOL D Command The following commands are used to configure and control the HOLD feature WINDow lt NRf gt Command syntax HOLD WINDow lt NRf gt Command Parameter lt NRf gt 0 01 to 10 Set window percent Query WINDow Query Hold window Description This command is used to set the window for HOLD This window is expressed as a percent of the seed reading for the Hold process COUNt lt NRf gt Command syntax HOLD COUNt lt NRf gt 42 Command Parameter TH1912 Operation manual lt NRf gt 2to100 Specify HOLD count Query COUNt Query HOLD count Descripton This command is used to specify the count for HOLD COUNt is the number of readings that are compared to the seed reading during the HOLD process STATe lt b gt Com

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