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Serial488A, OEM, and 512K

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1. nnag UD O00 SW1 L 5 6 11 Schematic C101 C105 C110 C113 C114 C117 C118 C119 C122 C123 C124 C201 C216 C217 C232 C233 D101 D102 D106 J101 J102 J103 J202 J203 R101 R102 R103 R104 R106 R201 R202 R204 R205 101 S102 S201 S202 U102 U103 U104 U105 U110 U113 U114 Part Number C 5 1 C 5 1 C 5 1 C 5 15p C 2 10 C 5 1 C 2 10 C5233 C 5 1 C 2 100 RF 1 DD 1 CN 11 CN 19 25 CN 2 CA 20 R 1 68K RN 4 4 7K RN 1 10K RN 2 470 R 1 1K RN 3 47 RN 1 10K SW 8 SW 6 8 SW 6 8 IC 10 IC 78 IC 23 IC 16 Macro488 601 IC 33 IC 82 6 12 6 11 Replaceable Parts List Serial488 512K Description 0 luF 25v ceramic 0 1uF 25v ceramic 0 1uF 25v ceramic I5pF ceramic 10uF 25v electrolytic Iub 25v ceramic 10uF 25v electrolytic 0 33uF 25v ceramic 0 luF 25v ceramic 100uF 25v electrolytic 1N914 diode LED Dialight 550 2406 Power Connector SWCR 712A 25 Pin Sub D Female IEEE Connector 20 Circuit Jumper Cable 68KQ 1 4w 10 carbon 4 7KQ x 7 SIP Network 10KQ X 9 SIP Network 470Q X 5 SIP Network 1KQ 1 4w 10 carbon 47 X 8 DIP Network 10KQ x 9 SIP Network Power Switch 8 pole DIP switch 8 pole DIP
2. 4 CP Cis 5 5 RIS 6 Ae6 7 gt 7 IBM AT to Serial488A Wiring Diagram RS 232 IBM ATto Serial488A DB 9 Female DB 25 Male DCD 1 RxD 2 XD 3 DIR 4 Gnd 5 DSR 6 RIS 7 A CTS 8 5 Note Standard AT 9 Pin to 25 Pin adapter cables are not wired as shown above and will not work with the Serial488A 2 21 2 9 General Operation Refer to the following sections for specific operational modes This sub section gives a general test of functionality After setting the power on defaults and reassembling the Serial488A plug the power supply connector into the rear jack on the interface CAUTION Never install the power supply into the interface while it is connected to AC line power Failure to observe this caution may result in damage to the Serial488A WARNING The power supply provided with the interface is intended for INDOOR USE ONLY Failure to observe this warning could result in equipment failure personal injury or death After installing the power supply connector into the interface plug the power supply into AC line power Place the rear panel power switch in the ON 1 position All the front panel indicators should light momentarily while the Serial488A performs an internal ROM and RAM self check At the end of this self check all indicators except POWER should turn off If there is an error in the ROM checksum all of the LE
3. 201 SW1 U 202 SW2 V 203 SW3 R2064 J J205 x L 3 C212 C213 N o T C211 C214 T e KR S U209 206 J Les Oo TZ N x m LO o ON CA 19 8 V 6 4 6 5 Replaceable Parts List Serial488A Schematic C101 C108 C110 C113 C117 C118 C124 C211 C214 C201 C203 C205 C209 C210 D101 D102 D106 J101 J104 J201 J204 J205 P204 R101 R102 R104 R201 R203 R205 R206 R207 201 S203 S205 U101 U102 U103 U104 U105 U106 U107 U108 U110 U113 U201 U203 U205 U206 U207 U208 U209 Y101 Part Number C 5 1 C 5 1 C 5 15p C 2 10 C 2 10 C 5 1 C 5 1 C 5 1 RF 1 DD 2 CN 2 CN 5 13 CN 11 CN 8 25 CA 19 8 CA 6 R 1 68K RN 4 4 7K RN 2 470 RN 1 10K R 2 39 R 1 100 R 1 1K SW 6 8 SW 11 IC 1 Serial488A 600 IC 78 IC 23 IC 16 IC 3 IC 4 IC 5 Macro488 601 IC 33 IC 39 IC 21 IC 30 IC 38 IC 36 IC 82 CR 4 Description Ceramic 25v Ceramic 25v Ceramic 25v Electrolytic 25v Electrolytic 25v Ceramic 25v Ceramic 25v Ceramic 25v Small Signal Diode Red PC Mount IEEE 488 Connector 13 x 2 0 1 Header 9 Volt Power Jack PC Mount Female DB 25 8 Pos DIP Jumper 26 Conductor Ribbon Assembly 68KQ 1 4w carbon 4 7KQ x 7 SIP 470Q x 5 SIP 10KQ x 9 SIP 39Q 1w carbon 100Q 1 4w carbon 1KQ 1 4w carbon 8 Pole DIP 8 Pole DT Push Push MC68BO09P Microprocessor
4. Controller issues an SPE Serial Poll enable command to each device sequentially If any device responds with DIO7 asserted it indicates to the Controller that it was the device that asserted SRQ Often times the other bits will indicate why the device wanted service This Serial Polling sequence and any resulting action is under control of the software designer 5 8 2 Parallel Poll The Parallel Poll is another way the Controller can determine which device requested service It provides the who but not necessarily the why When bus devices are configured for Parallel Poll they are assigned one bit on the data bus for their response By using the Status bit the logic level of the response can be programmed to allow logical OR AND conditions on one data line by more than one device When SRQ is asserted the Controller under user s software conducts a Parallel Poll The Controller must then analyze the eight bits of data received to determine the source of the request Once the source is determined a Serial Poll might be used to determine the why Of the two polling types the Serial Poll is the most popular due to its ability to determine the who and why In addition most devices support Serial Poll only 5 11 Service Information 6 1 Factory Service If problems are encountered in using the Serial488A you should first telephone the factory Many problems can be resolved by discussing the problems with our applications department
5. S202 B802 U203 T4HCT244 SW3 S203 E000 FFFF U102 2764 Programmed EPROM 6 2 3 U103 U102 port C O C D C103 C102 C117 cn oe OC Sea qe C101 C106 C107 C118 ee 6 3 Serial488A Mother Board Component Layout 6 3 6 4 Serial488A I O Board Component Layout CN 11 2 Er e E m m m m ni Er E E e m m m m ni i R205 OOOOOOOOOOOO OOOOOOOOOOOO S205 E fcd U207 U208 COT C208 U201 R201 C201 L C202 R202 D N3dO N3dO N3dO L9 9 v Z lI 9 S b E ah L9 S P Z I J204 Sc 8 NO
6. d IC 82 bai SS Q D lt o SO 1 40 el H s C C O8 Gg O N o 9 S S 4 Ml U101 2 EE 0 2 10 GEN T210 R102 C124 5 RN 4 4 7K E 2 oo So o I 6 10 a SW3 6 10 Serial488 512K I O Board Component Layout CBD QW BD e gt 87 0 q OE EA q E OvZLOHYA OL 00LOHPZ O amp gozn Lv NH q SL 992Lv E 8r Ol q O8 o s O ZLOHbL LG 0 CEO i Loan amp 6ozn 6eIS vA q vOSTrZ q gL 99Z LY SL 982y lend Q 8r 9l q Cs zozn 3 ozn OPZLOHbL G1 9S2 Ly GL 9S2 Lv 8 9 q 69 q t SeL 80S TbL E gozn z ol R 87 91 0 R d en ius S Q ozio MUS SL 99ZLv SL 9SZ Ly E ou e vozn om ER gi SL 99zLv SL 99Z Lv x gt 20 CND ZA sozn amp Sid rs T 23 4 5 6 7 8 Ga SI 98Z Lv lt OPEN 9 z AQ h 902n z d vien 8 9 MS 3 0 6 SL 99Z LY GL 9GZLb DEE ar Y S e yr21OHr o 402n 6 sizn Sy Eeer S1 96Z1 b SS R Z 123 45 67 8 S2 001 2 9 C amp eizn 3 A 12 SL 992L mE Hi REMS C C C F S O L 8 9 F S O
7. 15 for Class A devices If necessary refer to the FCC booklet How To Identify and Resolve Radio TV Interference Problems stock 004 000 00345 4 which is available from the U S Government Printing Office Washington D C 20402 CE Notice Many IOtech products carry the CE marker indicating they comply with the safety and emissions standards of the European Community As applicable we ship these products with a Declaration of Conformity stating which specifications and operating conditions apply Warnings and Cautions A Refer all service to qualified personnel This caution symbol warns of possible personal injury or equipment damage under noted conditions Follow all safety standards of professional practice and the recommendations in this manual Using this equipment in ways other than described in this manual can present serious safety hazards or cause equipment damage Zei This warning symbol is used in this manual or on the equipment to warn of possible injury or death from electrical shock under noted conditions electrostatic discharge Proper handling guidelines include the use of grounded anti static mats and wrist This ESD caution symbol urges proper handling of equipment or components sensitive to damage from A straps ESD protective bags and cartons and related procedures Specifications and Calibration Specifications are subject to change without notice Significant changes will be addressed in an addendum or re
8. 3 for more detailed information on the controller mode of operation 2 12 The Peripheral mode is used when interfacing a serial device to an IEEE controller Data which is sent by the IEEE controller to the Serial488A is transmitted out its serial port Data received from the serial device is buffered by the Serial488A until read by the IEEE controller Refer to Section 4 for more detailed information on the peripheral mode of operation The factory default is the IEEE Controller mode an RS 232 to IEEE converter SW2 View for Mode Selection ATA Drun DOT Controller Mode Peripheral Mode 2 6 IEEE Address Selection SW3 1 through SW3 5 select the IEEE bus address of the Serial488A when in the IEEE Peripheral mode These same switches are used in the IEEE Controller mode to select the address of the device that will be controlled Refer to Sections 4 and 3 respectively for additional information The address is selected by simple binary weighting with SW3 1 being the least significant bit and SW3 5 the most significant The factory default is address 10 Listen Only is a special type of Peripheral operation In the Listen Only mode the Serial488A accepts all data transmitted on the bus ignoring any bus addressing and transfers it out its serial port The Serial488A is set to Listen Only mode by setting its address to 31 If the IEEE address is set to 31 in the peripheral mode it is adjusted to 30 2 13 SW3 View for IEE
9. 33 IC 21 IC 39 IC 38 IC 36 IC 82 CR 4 Description Ceramic 25v Ceramic 25v Ceramic 25v Electrolytic 25v Ceramic 25v Small Signal Diode Red PC Mount IEEE 488 Connector 12 x 2 0 1 Header 2 Position power connector PC Mount Female DB 25 8 Pos DIP Jumper 4 7KQx 7 SIP 68KQ 1 4w carbon 1KQ 1 4w carbon 470Q x 5 SIP 100Q 1 4w carbon 10KQ x 9 SIP 8 Pole DIP MC68BO09P Microprocessor Programmed EPROM 84256 15 32K x 8 CMOS SRAM 65B22 Versitile Interface Adapter R6551AP UART TMS9914ANL IEEE Controller SN75160BN IEEE Driver SN75162BN IEEE Driver Programming Equation 16L8 PAL 74LS04 Hex Inverter SN74LS139 Dual Decoder 74HCT244 Octal Buffer 26LS30 RS 423 Driver 26LS33 RS 422 Receiver LT1081 RS 232 Transceiver 7 3728 MHz Crystal 6 9 6 9 Serial488 512K Motherboard Component Layout g g el g g H e v i g e o o o g N m M N ek N N o SO 1 40 m D d S b 74LS04 SE E 6522 o 1 33 e IC 23 gt os S a wo N x Z 2 SE SO 1 28 U105 CN 5 13 i Ei gt 6551 E e 2 ooooooooooooo L Jolo IC 16 we eg E J104 a 7 SO 1 20 SO 1 28 B 16L8 PAL E a Macro488 601 e ee Oo 84256 E n c 1 78 o gt EH wo 7 Ch 9 AS SO 1 28 c 5 A N Oe 9 LT1081
10. If no serial character has been received by the end of this time the IEEE bus device is addressed to talk The choice of talk back modes depends strongly on the type of device and software being used For most plotter applications the Talk back on Time Out feature should be enabled When the last IEEE bus terminator is detected from the IEEE device the Serial488A disables the device from sending additional information by asserting Attention ATN on the bus If the IEEE device does not respond or finish transmission by the time additional characters are received into the serial input buffer the talk sequence will be aborted to allow additional serial information to be sent to the IEEE device Most IEEE 488 plotters will not respond to the talk address sequence with output data unless there has been a specific device dependent command sent to tell them what to say If they have not been told what to say they say nothing 3 5 The following is an example of how this feature can be used to communicate with an IEEE plotter The program example is written in Basic on an IBM PC or compatible It turns the PC into a dumb serial terminal When a key is pressed on the keyboard the character is transmitted out of the serial COMI port Any serial data which is received from the port is printed on the display 10 Dumb Terminal Program for the Serial488A 20 This Program allows direct interaction between 30 the IBM PC and an IEEE plotter thr
11. If the problem cannot be solved by this method you will be instructed as to the proper return procedure 6 2 Theory of Operation The Heart of the Serial488A is a 6809 microprocessor U101 supported by 8K bytes of firmware EPROM U102 2764 and 32K bytes of static RAM U103 58256 A Versatile Interface Adapter U104 65B22 is used to generate real time interrupts for the firmware operating system The front panel annunciators are also driven by U104 through an inverter U113 74LS04 The IEEE 488 bus interface is accomplished by a TMS9914A U106 controller with drivers U107 and U108 The serial interface is provide by the UART 6551 U105 If RS 232 levels are chosen they are provided by the RS 232 transceiver U209 If RS 422 levels are selected the differential driver 26L S30 U207 and receiver 26LS33 U208 are used The internal DIP switches SW1 SW2 and SW3 are read via 74HCT244 tri state buffers U201 U202 and U203 Power is supplied by an external unregulated 9 volt wall mount supply Regulation to the required 5 volts is provided by U206 7805 6 1 Decoding of the microprocessor address space is accomplished with a Programmable Logic Array U110 16L8 The Memory space allocation is Address Device Part Number Function 0000 7 FFF U103 58258 Static RAM A000 A007 U106 9914A IEEE Controller A800 A807 U105 6551 UART B000 BOOF U104 65B22 VIA B800 U201 T4HCT244 SW S201 B801 U202 T4HCT244 SW2
12. SRQ switch located on the internal switch bank of SW1 must be enabled When enabled the Serial488A will assert the IEEE bus SRQ line and set serial poll status bits DIO7 and DIO3 when the last serial terminator is detected The IEEE controller must perform a serial poll on the interface to clear the SRQ If the Peripheral SRQ switch is in the disabled position there will still be an indication in the serial poll status byte that the last serial input terminator was received but Serial488A will not generate a service request SRQ SW1 View For Selecting SRQ on Last Terminator Wl Wl OPEN OPEN SRQ on Last SRQ on Last Terminator Disabled Terminator Enabled 4 4 Serial Poll Status Byte Register The following shows and describes the serial poll status information provided by the Serial488A DIOS IEEE Input Buffer NOT Empty This bit is set when the IEEE input buffer contains one or more data bytes which have not been sent out the serial port It is cleared set to 0 when the buffer is empty 4 4 DIO7 DIO6 DIO5 Serial Poll Status Byte 128 64 32 16 8 4 2 1 DIO8 DIO7 DiO6 pIos5 DIO 4 DIO3 DIO2 DIO1 Lk gt ij e gt _ O g e 4 Q G o 2 um 5 au ge E S E P G Ss 5 5 T Ti S eo lt 2 3 T D lt D s 1 D ea WwW G 2 KS o Ka O d Ss BC Bg B 5 O o w LLI o 2 5 2 TE be c am E LLI ac LLI m LLI 3 q rsv
13. Unasserted Getting Started 2 1 Inspection The Serial488A was carefully inspected both mechanically and electrically prior to shipment When you receive the interface carefully unpack all items from the shipping carton and check for any obvious signs of physical damage which may have occurred during shipment Immediately report any such damage found to the shipping agent Remember to retain all shipping materials in the event that shipment back to the factory becomes necessary Every Serial488A is shipped with the following Serial488A IEEE 488 Bus Converter 140 0920 Instruction Manual Power Supply 9 Volt Regulated TR 2 115V or TR 2E 220V Every Serial488A OEM is shipped with the following Serial488A OEM IEEE 488 Bus Converter 140 0920 Instruction Manual Every Serial488 512K is shipped with the following Serial488 512K IEEE 488 Bus Converter 140 0920 Instruction Manual Power Supply 9 Volt Regulated TR 2 115V or TR 2E 220V 2 1 2 2 Configuration Three DIP switches internal to the Serial488A set the configuration of the interface NOTE Selectable functions are read ONLY at power on and should only be set prior to applying power to the interface The following figures illustrate the factory default settings which are Serial Port IEEE 9600 Baud Mode IEEE 488 Controller 8 Data Bits Address 10 2 Stop Bits Bus Terminator LF EOI Disabled No Parity Talk back on Terminator Enab
14. does this by preventing completion of the bus handshaking sequences It will also request that additional serial data not be sent by negating its Request To Send RTS output or by transmitting the Xoff ASCII character The serial handshake used is dependent on the handshake selection Refer to Section 2 4 2 Serial and IEEE Input Buffers Memory in the Serial488A is dynamically allocated for the serial input and IEEE input buffers This allows for the most efficient partitioning of memory for any given application At power on or device clear each buffer is allocated a 128 byte mini buffer or queue When the serial input or IEEE input requires more buffer space additional queues are allocated When a queue is empty it is released from the input buffers so that it may be re allocated when and where required There are approximately 250 available queues in the Serial488A and the Serial488A OEM for a total of 32 000 bytes of buffer character space Queues are continually allocated and released as required by the serial and IEEE input Of the 250 available queues 240 are issued without regard to controlling the receipt of additional serial or IEEE input data 4 1 When the serial input buffer requests one of the last 10 queues 1280 character locations left it signals the serial host that it should stop sending data This is accomplished by either un asserting RTS or issuing Xoff depending on which serial handshake control has be
15. 75 O Colorwriter 6320 ra H P 7550A j O Epson HI 80 C3 H P 7570A DraftPro O Facit 4551 im H P 75306 O Graphtec FP5301 C7 H P 7585B 3 11 A Macintosh based Graphics System Serialda8B The Macintosh computer outputs RS 422 levels Because of this the internal DIP shorting jumper is set to the RS 422 position J205 Selecting RS 422 Signal Levels Serial488A 3 12 Selecting RS 422 Signal Levels Serial488A OEM 901 Oooooooo RS 232 foo 4 OoOOoOoooooog COT RS422 IAANAAAAN Shorting Plug 3 13 The following illustrates the Serial488A s internal switch settings for use with MacPlot utilizing the previously described format Serial488A Settings For Use With HP 7580A Plotter on a Macintosh IEEE Term CR EO Enabled Mode c x Talk Back on Time Out Enabled Serial Term R Echo No Echo Parity No Parity Baud Rate mE Handshake Xon Xoff Word Length 7 Data Bits Talk Back on Terminator Enabled Stop Bits Stop Bit 3 14 After configuration turn on the plotter and the Serial488A The Serial488A s front panel LEDs should all light momentarily while it performs an internal ROM and RAM test All LEDs should go out except for the Power and Talk LED The Talk LED indicates that the Serial488 has detected the plotter on the IEEE bus and has addressed it to listen When the serial host begins to send the Serial488 data the Receive LED will flash
16. Address 10 3 4 Talk Back Features Two different switch selectable talk back features are included to provide bi directional communication with the IEEE device Whether either talk back feature should be enabled is dependent on the application 3 4 1 Talk Back On Terminator SWI 7 is used to determine whether the interface should address the attached bus device to talk after sending the selected IEEE bus terminator s This feature is commonly used to provide bi directional communication with a single IEEE instrument Talk back will only occur if there is no serial data to output to the IEEE device The factory default is Talk back On Terminator enabled SW View for Talk Back on Terminator Selection Talk Back on Talk Back on Teminator Disa bled Teminator Enabled 3 3 When the serial input buffer becomes empty the Serial488A checks the last characters sent to the IEEE bus device If these were the IEEE bus terminators and Talk Back on Terminator is enabled the IEEE bus device is addressed to talk Any data received by the Serial488A from the bus device is sent to the serial host When the last IEEE bus terminator is detected from the IEEE device the Serial488A disables the device from sending additional information by asserting Attention ATN on the bus If the IEEE device does not responded or finish transmission by the time additional characters are received into the serial input buffer the talk sequence will be aborted
17. D Acceptor NDAC Acceptor IEEE Bus Handshaking 5 6 DATA LINES The GPIB provides eight data lines for a bit parallel byte serial data transfer These eight data lines use the convention of DIO1 through DIOS instead of the binary designation of D0 to D7 The data lines are bidirectional and are active low 5 7 MULTILINE COMMANDS Multiline bus commands are sent by the Active Controller over the data bus with ATN asserted These commands include addressing commands for talk listen Untalk and Unlisten 5 7 1 Go To Local GTL This command allows the selected devices to be manually controlled 01 5 7 5 7 2 Listen Address Group LAG There are 31 0 to 30 listen addresses associated with this group The 3 most significant bits of the data bus are set to 001 while the 5 least significant bits are the address of the device being told to listen 5 7 3 Unlisten UNL This command tells all bus devices to Unlisten The same as Unaddressed to Listen 3F 5 7 4 Talk Address Group TAG There are 31 0 to 30 talk addresses associated with this group The 3 most significant bits of the data bus are set to 010 while the 5 least significant bits are the address of the device being told to talk 5 7 5 Untalk UNT This command tells bus devices to Untalk The same as Unaddressed to Talk 5F 5 7 6 Local Lockout LLO Issuing the LLO command prevents manual control of the instrument s functions 11 5 7 7 Dev
18. Ds will remain on Flashing LEDs indicates a RAM failure Should such an error occur turn the rear panel switch to the OFF 0 position and retry the above procedure When the Serial488 512K is first powered on it performs a self test which lasts approximately 15 seconds The front panel LED s will flash while the self test is performed If the unit is functional all LED s except power should turn off after the self test is completed If one or more LED s remains flashing refer to the Hardware Fault Identification Table to determine the cause of error 2 22 Hardware Fault Identification Table Serial488 512K Error Talk Listen Empty Full Power No Error off off on off on No Error Listen Only off on on off on No Power off off off off off Program Rom on on on on on Ram U209 blink off off off on Ram U210 blink off on off on Ram U211 blink off off on on Ram U212 blink off on on on Ram U213 blink on off off on Ram U214 blink on on off on Ram U215 blink on off on on Ram U216 blink on on on on Ram U208 off off off blink on Ram U201 off off on blink on Ram U202 off on off blink on Ram U203 off on on blink on Ram U204 on off off blink on Ram U205 on off on blink on Ram U206 on on off blink on Ram U207 on on on blink on Logic Error blink blink blink blink on 2 23 If the front panel indicators do not flash and the POWER indicator does not remain lit there may not be any power supplied to the interface In
19. E Address Selection IEEE Address 10 2 7 Feature Selections The functions of the remaining switches are dependent on the mode selected A brief description of each of these features follows You should refer to the listed sections for additional information 2 7 1 Controller Features In the IEEE Controller RS 232 to IEEE 488 Converter mode SW1 7 is used to determine whether the interface should after sending the IEEE bus terminators address the attached bus device to talk The factory default is Talk back On Terminator enabled SW2 2 selects whether the Serial488A should address the attached bus device to talk when the Serial488A has nothing more to send to that device The factory default is Talk back On Time Out enabled Refer to Section 3 for complete details on these features SW1 View for Controller Talk Back on Terminator Selection Wl OPEN Talk Back on Talk Back on Teminator Disabled Teminator Enabled SW2 View for Controller Talk Back on Time Out Selection ll OPEN Talk Back on Talk Back on Time Out Disabled Time Out Enabled 2 7 2 Peripheral Features In the IEEE Peripheral IEEE 488 to RS 232 converter mode SW1 7 enables the interface to assert the SRQ IEEE bus interface line to indicate that it has received the last switch selected serial terminator character from the serial device SW1 View for Peripheral SRQ on Last Serial Terminator SRQ on Last SRQ on Last Teminator Disa bled Temina
20. I value of 13 when its buffer memory is near full When issued there is greater than 1000 character locations remaining to protect against buffer overrun When it is able to accept more information it issues an Xon character ASCII value of 11 The Serial488A also accepts Xon Xoff on transmit from the serial host it is communicating with RTS CTS serial control becomes inactive when Xon Xoff is enabled The RTS output is however set to an active high state The CTS input is not used for this handshake and may be left floating unconnected With RTS CTS the Serial488A un asserts RTS low when its buffer memory is near full When un asserted there is greater than 1000 character locations remaining to protect against buffer overrun When it is able to accept more information it asserts high RTS The Serial488A will not transmit data to the serial host if it detects the CTS input un asserted low when configured for this hardware handshake The factory default serial control is hardware RTS CTS SW1 View for Serial Handshake Selection INI TE RTS CTS Xon Xoff 2 10 2 4 Terminator Selection The Serial48SA can be configured to provide RS 232 to IEEE 488 and IEEE 488 to RS 232 terminator substitution This is useful when interfacing an RS 232 device which only issues carriage return CR as an output terminator to an IEEE controller which expects a carriage return followed by a line feed CR LF In the above example the s
21. If it does not this indicates that the interface is not receiving data from the serial host Verify the cables are connected properly and the serial cable wiring Verify the serial data format word length stop bits and parity 3 6 Printer Applications Most of the information given for plotter applications applies to applications for interfacing IEEE 488 printers to a serial host Some high end printers have a secondary command setting which must be disabled for the Serial488A to control them The Serial488 does not use secondary commands to control IEEE peripherals such as printers or plotters Refer to the printer s instruction manual if the is a question as to whether the printer requires secondary commands 3 15 Peripheral Operation 4 1 Peripheral Mode Operation This mode of operation is useful in interfacing a serial device such as a serial printer plotter or instrument to an IEEE controller Data which is sent by the IEEE controller to the Serial488A is buffered and transmitted out its serial port Data received from the serial device is buffered by the Serial488A until read by the IEEE controller The Serial488A and the Serial488A OEM can buffer approximately 32 000 bytes of data from both the IEEE input and the serial input The Serial488 512K can buffer 512 000 bytes of data from both the IEEE input and the serial input The Serial488A will refuse to accept more data from the IEEE controller when its buffer memory is full It
22. M PC running GWBasic with the IOtech Personal488 controller package Communications are provided under direct interaction from the keyboard In this program example key presses are detected and sent via the IEEE bus to the Serial488A The character is then sent to the serial device Any incomming serial characters are buffered by the Serial488A The Serial488A is polled by the controller for any data in the serial input buffer When data is detected it is read by the controller one character at a time and printed on the PC s screen The IEEE address of the Serial488A is 10 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 SS 160 Open Driver488 Files and initialize OPEN DEV IEEEOUT FOR OUTPUT AS 1 IOCTRL 1 BREAK PRINT 1 RESET OPEN DEV IEEEIN FOR INPUT AS 2 Look for PC Key Press KS INKEYS IF K THEN GOTO 110 Output Key Press to Serial488A PRINT l OUTPUT 10 KS Test for Serial data PRINT 1 SPOLL 10 INPUT 2 SPOLL IF NOT SPOLL AND 16 THEN GOTO 70 Enter One Byte From Serial488A and print it PRINT H1 ENTER 10 41 SS INPUTS I l PRINT GOTO 120 Try for more 4 10 IEEE 488 Primer 5 1 HISTORY The IEEE 488 bus is an instrumentation communication bus adopted by the Institute of Electrical and Electronic Engineers in 1975 and revised in 1978 The Serial488A conforms to this most recent revision designated IEEE 488 1978 Prior to the adoption of this stan
23. Programmed EPROM 84256 15 32K x 8 CMOS SRAM 65B22 Versitile Interface Adapter R6551AP UART TMS9914ANL IEEE Controller SN75160BN IEEE Driver SN75162BN IEEE Driver Programming Equation 16L8 PAL 74LS04 Hex Inverter 74HCT244 Octal Buffer SN74LS139 Dual Decoder LM7805CT Regulator 5v 26LS30 RS 423 Driver 26LS33 RS 422 Receiver LT1081 RS 232 Transceiver 7 3728 MHz Crystal 6 5 Section 6 Service Information 6 6 Seriald88A OEM Component Layout o00000000 99 900922 8 a M xA xs Jill e S 2a T eeng 0108 t C Se 6 6 imensions 6 7 Serial488A OEM Mechanical D 8 Nn va 087 s loH Se oH Bununo N Bununo N se eld v eg 9S1 0 DEE 6 7 IEEE Connector Mounting amp Hole Punch Out Q C 0 200 Radius typ G lt D a dia 2 places Note Does not imply orientation 6 8 6 8 Replaceable Parts List Serial488A OEM Schematic C101 C114 C116 C118 C119 C120 C121 C125 C126 D101 D102 D106 J101 J102 J103 J104 J105 R101 R102 R103 R104 R105 R106 R108 101 S103 U101 U102 U103 U104 U105 U106 U107 U108 U109 U110 U111 U112 U114 U116 U117 U118 Y101 Part Number C 5 1 C 5 1 C 5 15p C 2 10 C 5 1 RF 1 DD 2 CN 2 CN 5 12 CN 32 2 CN 8 25 CA 19 8 RN 4 4 7K R 1 68K R 1 1K RN 2 470 R 1 100 RN 1 10K SW 6 8 IC 1 Serial488A 600 IC 78 IC 23 IC 16 IC 3 IC 4 IC 5 Macro488 601 IC
24. Serial488A Serial488A OEM Serial488A 512K User s Manual IOtech Inc 25971 Cannon Road Cleveland OH 44146 Phone 440 439 4091 Fax 440 439 4093 E mail sales iotech com Internet http www iotech com Serial488A Serial488A OEM Serial488 512K User s Manual pin SERIAL488 A 901 Rev 2 3 1998 by IOtech Inc Printed in the United States of America Warranty Your IOtech warranty is as stated on the product warranty card You may contact IOtech by phone fax machine or e mail in regard to warranty related issues Phone 440 439 4091 fax 440 439 4093 email sales 21otech com Limitation of Liability IOtech Inc cannot be held liable for any damages resulting from the use or misuse of this product Copyright Trademark and Licensing Notice All IOtech documentation software and hardware are copyright with all rights reserved No part of this product may be copied reproduced or transmitted by any mechanical photographic electronic or other method without IOtech s prior written consent IOtech product names are trademarked other product names as applicable are trademarks of their respective holders All supplied IOtech software including miscellaneous support files drivers and sample programs may only be used on one installation You may make archival backup copies FCC Statement IOtech devices emit radio frequency energy in levels compliant with Federal Communications Commission rules Part
25. This bit is defined by the IEEE 488 Specification and is used to indicate to the bus controller that the Serial488A is the bus device that requested service It is cleared when the interface is serial polled by the controller Not Defined Always 0 Serial Input Buffer NOT EMPTY This bit is set when the serial input buffer contains one or more data bytes which have not been sent out the IEEE bus It is cleared set to 0 when the buffer is empty 4 5 DIO4 IEEE Input Buffer Full When this bit is set it indicates that the Serial488A may hold off the controller on subsequent data transfers The interface may continue to accept an additional 512 characters but this is dependent on the serial input buffer size DIO3 Received Last Serial Terminator This bit is set 1 when the Serial488A detects the last serial terminator at its serial input It remains set as long as there is at least one serial terminator in the serial input buffer If the Peripheral SRQ feature is enabled the Serial488A will issue a request for service by asserting the SRQ line and also set the rsv bit DIO7 The rsv bit is cleared along with the SRQ line when serial polled by the controller If there are additional serial terminators in the serial input buffer Serial488A will reassert the SRQ line and rsv bit when the last IEEE 488 bus terminator is sent to the IEEE 488 controller DIO2 Serial Handshake This bit indicates the present state of the serial handsha
26. a 0D 13 CR we 2 2 2 2 2 SP 0 1 3 O 1 2 3 2 3 3 3 3 4 5 3 U 5 6 3 S amp 6 3 q 07 08 8 18 28 40 38 48 72 58 88 568 104 78 cae a a rie PE 08 2 08 24 SCG SCG 91 29 41 39 49 73 59 89 569 105 79 EET cy j PD 09 2 09 25 SCG SCG A 42 d 0 B B 4 1 c C 4 H 2 D D 4 3 E E 4 4 F 4 5 U 0E 14 3E 4E 78 SE 94 SOE 110 7E zu REM CN EN TM 3 4 30 SCG SCG SOF 15 1F 3F 4F 79 SF 95 bet 111 7F 127 E MIC NN U 5 UNT SCG SCG ACG LAG TAG SCG ACG Addressed Command Group TAG Talk Address Group UCG Universal Command Group SCG Secondary Command Group LAG Listen Address Group B 1
27. connector The Serial488A s connector is configured as DCE type equipment for RS 232 communications which means the Serial488A always transmits data on Pin 3 and receives data on Pin 2 The following list describes the RS 232 and RS 422 signals provided on the Serial488A Note since the Serial488 512K does not support RS 422 communication the pins labeled TxD and RxD are not used Any reference to RS 422 communication does not apply to the Serial488 512K 2 17 RxD TxD CTS Rear View of the Serial488A s Serial Connector o Q w QAQwnnaa ZRFEEXX Oz orm 13 1 25 14 TXD RXD Receive Data Input Pin 2 This pin accepts serial data sent by the RS 232 or RS 422 host The serial data is expected with the word length baud rate stop bits and parity selected by the internal switches The signal level is low true Transmit Data Output Pin 3 This pin transmits serial data to the RS 232 or RS 422 host The serial data is sent with the word length baud rate stop bits and parity selected by the internal switches The signal level is low true Clear To Send Input Pin 4 The CTS input is used as a hardware handshake line to prevent the Serial488A from transmitting serial data when the RS 232 host is not ready to accept it When RTS CTS handshake is selected on the internal switches the Serial488A will not transmit data out TxD while this line is un asserted low If the RS 232 host is not capable
28. d of performing serial polls When serial polled the Serial488A provides eight bits of status information to the controller The most significant bit DIO8 of the Serial488A s serial poll byte is set to a logic 1 when the IEEE input buffer is NOT EMPTY The term NOT EMPTY is used to signify that not all of the previous data sent to the interface has been transmitted to the serial device If it is NOT EMPTY the controller may avoid sending any more data to the Serial488A If this bit is a logic 0 then the serial device has accepted all previous data and the IEEE controller may send more Another bit DIO4 of the Serial Poll byte is used to indicate additional information concerning the IEEE input buffer This bit is set to a logic 1 when there is 1280 or less locations in the buffer for data It is cleared set to a logic 0 when there is greater than 1280 locations available This bit is referred to as the IEEE input buffer FULL bit 4 3 When serial data is received DIOS of the Serial Poll byte is set 1 to indicate to the IEEE controller that the serial input buffer is NOT EMPTY If set it indicates that at least one character is available in the serial input buffer to be read by the IEEE controller Once all of the serial input data is read by the IEEE controller this bit is reset The Serial488A can generate a request for service on the bus when it receives the last serial terminator To enable this feature the Peripheral
29. dard most instrumentation manufacturers offered their own versions of computer interfaces This placed the burden of system hardware design on the end user If his application required the products of several different manufacturers then he might need to design several different hardware and software interfaces The popularity of the IEEE 488 interface sometimes called the General Purpose Interface Bus or GPIB is due to the total specification of the electrical and mechanical interface as well as the data transfer and control protocols The use of the IEEE 488 standard has moved the responsibility of the user from design of the interface to design of the high level software that is specific to the measurement application 5 2 GENERAL STRUCTURE The main purpose of the GPIB is to transfer information between two or more devices A device can either be an instrument or a computer Before any information transfer can take place it is first necessary to specify which will do the talking send data and which devices will be allowed to listen receive data The decision of who will talk and who will listen usually falls on the System Controller which is at power on the Active Controller The System Controller is similar to a committee chairman On a well run committee only one person may speak at a time and the chairman is responsible for recognizing members and allowing them to have their say On the bus the device which is recognized to speak i
30. defined by the IEEE 488 1978 specification These are discussed in the following sections The bus uniline and multiline commands that the Serial488A does not support or respond to include Remote Enable REN Go to Local GTL Group Execute Trigger GET Local Lockout LLO Take Control TCT Parallel Poll PP Parallel Poll Configure PPC Parallel Poll Unconfigure PPU Parallel Poll Disable PPD 4 6 1 My Talk Address MTA When the Serial488A is addressed to talk it retrieves data from the serial input buffer and outputs it to the IEEE 488 bus It substitutes the selected IEEE bus terminators for the received serial terminators The Serial488A will continue to output serial input buffer data as long as the IEEE controller allows 4 6 2 My Listen Address MLA 4 7 When the Serial488A is addressed to listen it accepts data from the active talker and outputs this data through the serial interface It substitutes the selected serial terminators for the received IEEE bus terminators 4 6 3 Device Clear DCL and SDC Device Clear resets the Serial488A s IEEE input and serial input buffers Any pending data and Service Requests SRQ including the information they convey are lost 4 6 4 Interface Clear IFC IFC places the Serial488A in the Talker Listener Idle State It clears any pending requests for service SRQ The condition which caused the SRQ remains unmodified 4 6 5 Serial Poll Enable SPE When Serial P
31. en switch selected When more than 10 queues become available it asserts RTS or issues Xon The IEEE bus input signals that the IEEE input or serial output buffer is full when the number of queues available drops below 10 1280 character locations left When the number of available queues drops to 4 or less 512 character locations left the IEEE interface of the Serial488A stops accepting data from the bus This bus hold off will only occur until additional queues greater than 4 become available At that time it will resume accepting bus data 4 3 IEEE Data Transfers The following methods may be used by the IEEE controller when sending data to the Serial488A 4 3 1 Blind Bus Data Transfers If the IEEE controller does not mind waiting an indefinite time for data space in the buffer to become available the data can simply be sent to the Serial488A This is referred to as blind data transfers because the IEEE controller is blind as to whether or not the Serial488A is capable of accepting data In this case the bus controller s output data transfer will be held off by the Serial488A if it is unable to buffer the data It will resume accepting IEEE input data when memory becomes available This type of control might be appropriate in a single user environment To illustrate how this would appear let s assume the Serial488A is connected to a serial device which will accept data at 1200 baud or 110 bytes per second The IEEE bus control
32. erial terminator should be selected for CR Only while the IEEE terminator is set to CR LF When a serial CR character is received it is discarded and substituted with an IEEE CR LF In the IEEE to RS 232 direction the IEEE CR is unconditionally discarded Upon receipt of the IEEE LF a serial CR is substituted The Serial488A can be made totally data transparent by setting both the serial and IEEE terminators to be CR Only or LF Only 2 4 1 Serial Terminator Selection SW2 3 and SW2 4 select the serial terminators for the serial input and output The factory default is LF Only SW2 View for Serial Terminator Selection mmm men DOT CR Only LF CR LF Only CR LF 2 11 2 4 2 IEEE Bus Terminator Selection SW3 6 through SW3 8 set the IEEE bus terminators used for data sent or received by the Serial488A EOI a line used to signal the end of a multiple character bus transfer may also be enabled If enabled EOI is asserted when the last selected bus terminator is sent Factory default is LF Only with EOI disabled SW3 View for IEEE Bus Terminator Selection 1 2 3 Ia EOI Disabled EOI Enabled 2 5 Mode Selection SW2 1 sets the major operating mode of the Serial488A The IEEE Controller RS 232 to IEEE Converter mode allows a serial host device to send data to a single IEEE bus peripheral Applications include interfacing a listen only or addressable IEEE printer plotter to a serial printer port Refer to Section
33. h device configurations vary the IFC command usually places the devices in the Talk and Listen Idle states neither Active Talker nor Active Listener 5 4 3 Remote Enable REN When the System Controller sends the REN command bus devices will respond to remote operation Generally the REN command should be issued before any bus programming is attempted Only the System Controller has control of the Remote Enable line 5 4 4 End or Identify EOD The EOI line is used to signal the last byte of a multibyte data transfer The device that is sending the data asserts EOI during the transfer of the last data byte The EOI signal is not always necessary as the end of the data may be indicated by some special character such as carriage return The Active Controller also uses EOI to perform a Parallel Poll by simultaneously asserting EOI and ATN 5 4 5 Service Request SRQ When a device desires the immediate attention of the Active Controller it asserts SRQ It is then the Controller s responsibility to determine which device requested service This is accomplished with a Serial Poll or a Parallel Poll 5 5 5 5 HANDSHAKE LINES The GPIB uses three handshake lines in an I m ready Here s the data I ve got it sequence This handshake protocol assures reliable data transfer at the rate determined by the slowest Listener One line is controlled by the Talker while the other two are shared by all Active Listeners The handshake lines
34. hich only issues carriage return CR as an output terminator to an IEEE peripheral which expects a carriage return followed by a line feed CR LF In this previous example the serial terminator should be selected for CR Only while the IEEE terminator is set for CR LF When a serial CR character is received it is discarded and substituted with an IEEE CR followed by an IEEE LF In the IEEE to serial direction the IEEE CR is unconditionally discarded Upon receipt of the IEEE LF a serial CR is substituted The Serial488A can be made totally data transparent by setting both the serial and IEEE terminators to be CR Only or LF Only Refer to Section 2 for the proper switch settings for both the IEEE and serial terminators 3 3 IEEE Address Selection SW3 1 through SW3 5 select the IEEE bus address of the IEEE peripheral the Serial488A will be communicating with These switches set the address of the IEEE device that will be controlled not the address of the Serial488A The address of the Serial488A is automatically adjusted so that address conflicts will not occur The address is selected by simple binary weighting with SW3 1 being the least significant bit and SW3 5 the most significant If address 31 reserved on the IEEE bus is selected in the controller mode address 30 is assigned as the device it will be communicating with The following figure shows the IEEE address selection of 10 3 2 SW3 View for IEEE Address Selection IEEE
35. ial488A OEM RS 232 lt Shorting Plug GOT OoOooooooo RS422 ICH c3 OOoOoOoOoOoOo 3 9 Serial488A Settings For Use With HP 7580A Plotter on an IBM PC EZ IEEE Addr s IEEE Term CR Only EO Enabled Mode c x Talk Back on Time Out Enabled Serial Term R Echo No Echo Parity Even Baud Rate 9900 Handshake Xem Xoff Word Length Daa Bits Talk Back on Terminator Enabled Stop Bits 1 Stop Bit 3 10 When using the Serial488A with plotting programs on the Macintosh computer with graphic drivers such as MacPlot some serial data format parameters are user modifiable The following is a partial MacPlot configuration screen which allows selection of baud rate stop bits and parity With this driver the word length is fixed to 7 data bits with Xon Xoff serial control These non modifiable defaults are plotter dependent Refer to the plotter or driver manual for the defaults of the specific plotter For this example 57600 baud with one stop bit and no parity has been chosen for the serial data format MacPlot Configuration Screen amp File Edit Windows EE X cEeEe Z SFE a Settings for HP 7580R Baud Rate 57600 Stop Bits 1 Parity None Paper Si Apple Plotter O Graphtec MP31 2 300 C Houst j O Calcomp 1044u 745 985 H P 7220 j 3 Calcomp 81 C3 H P 7440A ColorPro O Colorwriter 62000510 H P 7470A OQ Colorwriter 6310 O H P 74
36. ice Clear DCL This command causes all bus devices to be initialized to a pre defined or power up state 14 5 8 5 7 8 Selected Device Clear SDC This causes a single device to be initialized to a pre defined or power up state 04 5 7 9 Serial Poll Disable SPD The SPD command disables all devices from sending their Serial Poll status byte 19 5 7 10 Serial Poll Enable SPE A device which is Addressed to Talk will output its Serial Poll status byte after SPE is sent and ATN is unasserted 18 5 7 11 Group Execute Trigger GET This command usually signals a group of devices to begin executing a triggered action This allows actions of different devices to begin simultaneously 08 5 7 12 Take Control TCT This command passes bus control responsibilities from the current Controller to another device which has the ability to control 09 5 7 13 Secondary Command Group SCG These are any one of the 32 possible commands 0 to 31 in this group They must immediately follow a talk or listen address 60 to 7F 5 9 5 7 14 Parallel Poll Configure PPC This configures devices capable of performing a Parallel Poll as to which data bit they are to assert in response to a Parallel Poll 05 5 7 15 Parallel Poll Unconfigure PPU This disables all devices from responding to a Parallel Poll 15 5 8 MORE ON SERVICE REQUESTS Most of the commands covered both uniline and multiline are the responsibil
37. ine Messages 00 ok E20 32 30 S40 64 50 80 560 96 70 NUL P 0 00 6 SCG SCG 01 1 21 41 65 51 81 Sol 97 71 SOH A Q a GTL Li 0 01 7 SCG SCG 02 2 22 STX 0 P S S we 42 66 52 82 bei 98 72 Ke EE 02 8 SCG SCG 543 67 53 83 63 99 73 pr ae We 03 9 SCG SCG Ka Lo g a lt 4 ac 518 53 53 53 Ka we o D EI 10 16 2 48 112 DLE 0 p 6 17 3 31 49 113 DC1 1 q L 7 y 18 4 32 50 114 DC2 2 r 8 03 3 19 23 5 33 51 115 perpe 0 9 04 4 14 20 s24 6 34 52 44 68 54 84 s64 100 74 116 k Ch Kh CH CR Du il DCL 0 20 04 20 SCG SCG 05 5 21 525 7 35 53 s45 69 55 85 s65 101 75 117 GE ce Ch Da su P 0 21 05 21 ScG SCG 3 6 22 26 8 36 54 46 70 56 86 ken 102 76 118 H CHITA Ch Ga si 0 22 06 22 ScG ScG 07 7 17 23 27 9 37 55 47 71 57 87 s67 103 77 119 ie GS a a 23 07 23 SCG SCG 24 0 56 120 8 x 4 19 25 1 57 121 EM 9 y 5 5 26 2 58 122 3 Z 6 27 3 59 123 ESC 7 y 28 4 60 124 FS lt 8 29 5 61 125 GS 9 y 30 6 62 126 RS gt 0 31 7 63 US NL CG F 4 QD 4 SOA 10 2A 3A 4A 74 5A 90 56A 106 7A spe cp ecu 2 0 26 SCG SCG 0B 11 5 0C 12 d SEENEN we 3B 4B 75 5B 91 SOB 107 7B E UE 2 1 27 SCG SCG 3C 4C 76 5C 92 SoC 108 7C EE 2 2 28 SCG SCG 3D 4D TI 5D 93 6D 109 7D REN CHRON HS CRM 2 3 29 SCG SCG Ka K
38. ion is selected It is 180 out of phase with RxD Transmit Data Plus Output Pin 16 This pin transmits serial data to the RS 422 host The serial data is sent with the word length baud rate stop bits and parity selected by the internal switches The signal level is high true and only connected to this pin when RS 422 operation is selected It is 180 out of phase with TxD 2 19 2 8 3 Serial Cable Wiring Diagrams If a cable was not purchased with the interface the following diagrams will be helpful in making your own cable Simple soldering skills and an attention to detail will ensure successful construction Macintosh to Serial488A Wiring Diagram RS 422 Macintosh to Serial488A DB 9 Male DB 25 Male RIS 6 4 CTS CTS 7 h 5 RIS TxD 5 2 RD Gnd 3 7 Gnd RD 9 4 3 Da D 4 4 14 4Rxd 4RxD 8 4 16 Macintosh Plus SE II to Serial488A Wiring Diagram RS 422 Macintosh Il SE Plus to Serial488A Mini DIN8 Male DB 25 Male RIS 1 A4 cS 2 5 XD 3 2 Gnd 4 7 RxD 5 f 3 D 6 i4 RxD 8 amp V 16 2 20 IBM PC XT PS2 to Serial488A Wiring Diagram RS 232 IBM PC XT PS2 to Serial488A DB 25 Female DB 25 Male D 2 _ 2 RxD Ba 3 3 DND RS 4
39. ithin one system Each of these devices must have a unique address to avoid confusion In a similar fashion every building in town has a unique address to prevent one home from receiving another home s mail Exactly how each device s address is set is specific to the product s manufacturer Some are set by DIP switches in hardware others by software Consult the manufacturer s instructions to determine how to set the address Addresses are sent with universal multiline commands from the Active Controller These commands include My Listen Address MLA My Talk Address MTA Talk Address Group TAG and Listen Address Group LAG 5 4 BUS MANAGEMENT LINES Five hardware lines on the GPIB are used for bus management Signals on these lines are often referred to as uniline single line commands The signals are active low i e a low voltage represents a logic 1 asserted and a high voltage represents a logic 0 unasserted 5 4 1 Attention ATN ATN is one of the most important lines for bus management If Attention is asserted then the information contained on the data lines is to be interpreted as a multiline command If it is not then that information is to be interpreted as data for the Active Listeners The Active Controller is the only bus device that has control of this line 5 4 5 4 2 Interface Clear IFC The IFC line is used only by the System Controller It is used to place all bus devices in a known state Althoug
40. ity of the Active Controller to send and the bus devices to recognize Most of these happen routinely by the interface and are totally transparent to the system programmer Other commands are used directly by the user to provide optimum system control Of the uniline commands SRQ is very important to the test system and the software designer has easy access to this line by most devices Service Request is the method by which a bus device can signal to the Controller that an event has occurred It is similar to an interrupt in a microprocessor based system Most intelligent bus peripherals have the ability to assert SRQ A DMM might assert it when its measurement is complete if its input is overloaded or for any of an assortment of reasons A power supply might SRQ if its output has current limited This is a powerful bus feature that removes the burden from the System Controller to periodically inquire Are you done yet Instead the Controller says Do what I told you to do and let me know when you re done or Tell me when something is wrong Since SRQ is a single line command there is no way for the Controller to determine which device requested the service without additional information This information is provided by the multiline commands for Serial Poll and Parallel Poll 5 10 5 8 1 Serial Poll Suppose the Controller receives a service request For this example let s assume there are several devices which could assert SRQ The
41. ke If it is set to 1 the serial device connected to the Serial488A is capable of accepting serial data If O the RTS line is unasserted if configured for hardware handshake or the Xoff character has been received if configured for Xon Xoff software handshake DIO1 Not Used Always 0 4 5 Use of Serial and Bus Terminators The Serial488A can be configured to provide RS 232 to IEEE 488 and IEEE 488 to RS 232 terminator substitution This is useful when interfacing a serial device which only issues carriage return CR as an output terminator to an IEEE controller which expects a carriage return followed by a line feed CR LF 4 6 In the previous example the serial terminator should be selected for CR Only with the IEEE terminator set to CR LF When a serial CR character is received it is discarded and substituted with an IEEE CR followed by an IEEE LF In the IEEE to serial direction the IEEE CR is unconditionally discarded Upon receipt of the IEEE LF a serial CR is substituted The Serial488A can be made totally data transparent by setting both the serial and IEEE terminators to be CR Only or LF Only The choice of appropriate terminators may be determined by inspection of the serial device and IEEE controller s instruction manuals For selection of the Serial488A s serial and bus terminators you should refer to Section 2 of this manual 4 6 IEEE 488 Bus Implementation The Serial488A implements many of the capabilities
42. led Serial Terminator LF Talk back on Time Out Enabled Echo Disabled RTS CTS Handshake SW3 Factory Default Settings E RE IEEE Tem EOI Disa bled SW2 Factory Default Settings Talk Back on Time O ut Serial Term Echo No Echo Baud Rate 990 Handshake RI CTS Word Length 8 Data Bits TalkBackon Tem Enabled Stop Bits 2 Sto Bits The following drawings show the locations of switches SW1 SW2 and SW3 for the Serial488A Serial488A OEM and the Serial488 512K The top circuit board in the Serial488A and the Serial488 512K is referred to as the I O board 2 3 Serial488A Switch Location I O Board Serial488A OEM Switch Location TT S102 T 2 3 7 8 III se SW 6 8 103 iii e SW 6 8 2 4 Serial488 512K SW1 SW2 Location I O Board 8 9 MS 6 2I 0 rrZ1OHrZ d ni 301 L NH C e HUE Serial488 512K SW3 Location Motherboard 2 5 Note that the Serial488A comes configured as an IEEE controller In this mode the Serial488A is designed to allow an RS 232 computer to communicate with an IEEE peripheral such as a plotter This controller mode is described in detail in Section 3 The Serial488A may also be configured as an IEEE peripheral As an IEEE peripheral the Serial488A allows an IEEE controller to communicate with an RS 232 device The peripheral mode of operation is described in detail in Section 4 To modify any of these defaults follo
43. ler is capable of sending data to the Seriald88A at a rate of 5000 bytes per second The data would be transferred on the bus at 5000 characters per second for slightly over six seconds filling over 31 000 locations At that time the IEEE input would hold off additional data transfers until 128 characters are sent out the serial port at rate of 110 characters per second This 110 cps would then become the average bus data acceptance rate of the Serial488A If the controller is set to detect a data time out error then it will do so if the Serial488A holds off IEEE input data transfers for too long The 4 2 error can be used to alert the operator to the problem such as a printer out of paper so that it can be corrected If the controller then restarts transmission exactly where it left off no data will be lost If data is requested by the controller and no serial input data is available in the Serial488A the bus will hang until serial data is received If no serial data is received it will hang forever or until the controller times out 4 3 2 Controlled Bus Data Transfers If the controller must avoid waiting for the serial device it can serial poll the Serial488A Serial poll is a method by which the controller can inquire the internal status of the interface without disturbing any data being transferred slowing data transfers or locking up the bus You should refer to the programming manual of your controller to determine the metho
44. like the other IEEE 488 lines are active low 5 5 1 Data Valid DAV The DAV line is controlled by the Talker The Talker verifies that NDAC is asserted active low which indicates that all Listeners have accepted the previous data byte transferred The Talker then outputs data on the bus and waits until NRFD is unasserted high which indicates that all Addressed Listeners are ready to accept the information When NRFD and NDAC are in the proper state the Talker asserts DAV active low to indicate that the data on the bus is valid 5 5 2 Not Ready for Data NRFD This line is used by the Listeners to inform the Talker when they are ready to accept new data The Talker must wait for each Listener to unassert this line high which they will do at their own rate when they are ready for more data This assures that all devices that are to accept the information are ready to receive it 5 5 3 Not Data Accepted NDA C The NDAC line is also controlled by the Listeners This line indicates to the Talker that each device addressed to listen has accepted the information Each device releases NDAC high at its own rate but the NDAC will not go high until the slowest Listener has accepted the data byte 5 6 1st Data Byte 2nd Data Byte 4 hh TT x a Ky c T T E 7 E E e x x S DIO 1 8 composite DAV Source SS SS SS SS NRF
45. llel IEEE 488 panel mount feed through connector male and female IEEE 488 ABC switch 5 1 4 by 19 rack mount for one Serial488A 5 1 4 by 19 rack mount for two Serial488As Instruction Manual Specifications WARNING WARNING CAUTION Serial488A IEEE 488 CAUTION Terminal Installation Category Standard Not Applicable CE Category 1 Implementation C1 C2 C3 C4 and C28 controller subsets Serial to IEEE SHI AHI T6 TEO L4 LEO SR1 RLO PPO DC1 DTO El Terminators Selectable CR LF LF CR and CR LF with EOI Connector Standard IEEE 488 connector with metric studs Serial Interface Terminal Installation Category Standard Not Applicable CE Category 1 EIA RS 232C AB BA BB CA CB EIA RS 422A Balanced voltage on TxD and RxD Character Set Asynchronous bit serial Output Voltage 5 volts min RS 422A 5 volts typical RS 232C Input Voltage 3 volts min 15v max Baud Rate Selectable 110 300 600 1200 1800 2400 3600 4800 7200 9600 19 200 and 57 600 Data Format Selectable 7 or 8 data bits 1 or 2 stop bits odd even mark space and no parity on transmit Duplex Full with Echo No Echo Serial Control Selectable CTS RTS or XON XOFF Terminators Selectable CR LF LF CR and CR LF Connector 25 pin Sub D male DCE Configured General Terminal Installation Category Standard Not Applicable CE Category 1 for all terminals Data Buffer 32 000 characters dyna
46. mically allocated Indicators LEDs for IEEE Talk and Listen Serial Send and Receive and Power Power An external power supply is provided with the Serial488A Input is 105 to 125VAC 50 to 60 Hz 10 VA Maximum Dimensions 188mm deep x 140mm wide x 68mm high 7 39 x 5 5 x 2 68 Weight 1 55 kg 3 6 lbs Operating Environment Standard Indoor use 0 to 50 C 0 to 70 R H to 35 C Linearly derate 3 R H C from 35 to 50 C CE Indoor use at altitudes below 2000m 0 to 40 C 80 maximum RH up to 31 C decreasing linearly 4 RH C to 40 C Controls Power Switch external IEEE and Serial parameter switches internal Jumper selection of RS 232 or RS 422 operation internal Specifications subject to change without notice Serial488A OEM IEEE 488 Implementation Terminators Connector Serial Interface EIA RS 232C EIA RS 422A Character Set Output Voltage Input Voltage Baud Rate Data Format Duplex Serial Control Terminators Connector General Data Buffer Indicators Power Dimensions Weight Environment Controls C1 C2 C3 C4 and C28 controller subsets Serial to IEEE SHI AHI T6 TEO L4 LEO SR1 RLO PPO DC1 DTO El Selectable CR LF LF CR and CR LF with EOI Standard IEEE 488 connector with metric studs AB BA BB CA CB Balanced voltage on TxD and RxD Asynchronous bit serial 5 volts min RS 422A 5 volts typical RS 232C 3 volts
47. min 15v max Selectable 110 300 600 1200 1800 2400 3600 4800 7200 9600 19 200 and 57 600 Selectable 7 or 8 data bits 1 or 2 stop bits odd even mark space and no parity on transmit Full with Echo No Echo Selectable CTS RTS or XON XOFF Selectable CR LF LF CR and CR LF 25 pin Sub D male DCE Configured 32 000 characters dynamically allocated LEDs for IEEE Talk and Listen Serial Send and Receive and Power User supplied 5 volts 0 25 at 1 amp Mating power connector with 8 inch leads provided 205mm deep x 115mm wide x 28mm high 8 x 4 5 x 1 1 0 23kg 0 5 Ibs 0 50 C 0 to 7096 R H to 35 C Linearly derate 3 R H C from 35 to 50 C IEEE and Serial parameter switches Jumper selection of RS 232 or RS 422 operation Specifications subject to change without notice Serial488 512K IEEE 488 1978 Implementation Terminators Connector Serial Interface EIA RS 232C Character Set Output Voltage Input Voltage Baud Rate Data Format Duplex Serial Control Terminators Connector General Data Buffer Indicators Power Dimensions Weight Environment Controls C1 C2 C3 C4 and C28 controller subsets Serial to IEEE SHI AHI T6 TEO L4 LEO SR1 RLO PPO DC1 DTO El Selectable CR LF LF CR and CR LF with EOI Standard IEEE 488 connector with metric studs AB BA BB CA CB Asynchronous bit serial 5 volts typical RS 232C 3 v
48. of driving this line it can be connected to the Vtest output Pin 6 of the Serial488A If Xon Xoff handshake is selected the CTS line is not tested to determine if it can transmit data 2 18 RTS Vtest Gnd Vtest RxD TxD Request To Send Output Pin 5 The RTS output is used as a hardware handshake line to prevent the RS 232 RS 422 host from transmitting serial data if the Serial488A is not ready to accept it When RTS CTS handshake is selected on the internal switches the Serial488A will drive the RTS output high when there are greater than 1000 character locations available in its internal buffer If the number of available locations drops to less than 1000 the Serial488A will un assert low this output If Xon Xoff handshake is selected the RTS line will be permanently driven active high Test Voltage Output Pin 6 This pin is connected to 5 volts through a 1Ke resistor It is also common to Vtest on pin 9 Ground Pin 7 This pin sets the ground reference point for the other RS 232 inputs and outputs Test Voltage Output Pin 9 This pin is connected to 5 volts through a 1Ke resistor It is also common to Vtest on pin 6 Receive Data Plus Input Pin 14 This pin accepts serial data sent by the RS 422 host The serial data is expected with the word length baud rate stop bits and parity selected by the internal switches The signal level is high true and only connected to this pin when RS 422 operat
49. oll Enabled the Serial488A sets itself to respond to a serial poll with its serial poll status byte if addressed to talk When the serial poll byte is accepted by the controller any pending SRQs are cleared The Serial488A will continue to try to output its serial poll response until it is Serial Poll Disabled by the controller 4 6 6 Serial Poll Disable SPD Disables the Serial488A from responding to serial polls by the controller 4 8 4 6 7 Unlisten UNL UNL places the Serial488A in the Listener Idle State 4 6 8 Untalk UNT UNT places the Serial488A in the Talker Idle State 4 7 IEEE Address Selection SW3 1 through SW3 5 select the IEEE bus address of the Serial488A when in the IEEE Peripheral mode The address is selected by simple binary weighting with SW3 1 being the least significant bit and SW3 5 the most significant The following figure shows the IEEE address of the Serial488A set to 10 SW3 View for IEEE Address Selection IEEE Address 10 4 7 1 Listen Only Mode Listen Only is a special type of Peripheral operation In the Listen Only mode the Serial488A accepts all data transmitted on the bus and transfers it out its serial port The Serial488A is set to Listen Only mode by setting its address to 31 switches SW3 1 through SW3 5 all open 4 S IEEE to Serial Applications The following program uses a Serial488A as an interface to a serial instrument or host computer The IEEE controller is an IB
50. olts min 15v max Selectable 110 300 600 1200 1800 2400 3600 4800 7200 9600 and 19 200 Selectable 7 or 8 data bits 1 or 2 stop bits odd even mark space and no parity on transmit Full with Echo No Echo Selectable CTS RTS or XON XOFF Selectable CR LF LF CR and CR LF 25 pin Sub D male DCE Configured 512 000 characters LEDs for IEEE Talk and Listen Serial Send and Receive and Power 105 125V or 210 250V 50 60 Hz 10 VA Max 188mm deep x 140mm wide x 68mm high 7 39 x 5 5 x 2 68 1 95 kg 4 35 Ibs 0 50 C 0 to 7096 R H to 35 C Linearly derate 3 R H C from 35 to 50 C Power Switch external IEEE and Serial parameter switches internal Specifications subject to change without notice 1 6 Abbreviations The following IEEE 488 abbreviations are used throughout this manual addr n IEEE bus address n ATN Attention line CA Controller Active CO Controller CR Carriage Return data Data String DCL Device Clear GET Group Execute Trigger GTL Go To Local LA Listener Active LAG Listen Address Group LF Line Feed LLO Local Lock Out MLA My Listen Address MTA My Talk Address PE Peripheral PPC Parallel Poll Configure PPU Parallel Poll Unconfigure SC System Controller SDC Selected Device Clear SPD Serial Poll Disable SPE Serial Poll Enable SRQ Service Request TA Talker Active TAD Talker Address TCT Take Control term Terminator UNL Unlisten UNT Untalk
51. ough the 40 Serial488A The Serial488A must have talk back 50 on time out enabled 60 Open the serial communications port 70 OPEN COM1 9600 n 8 2 cs ds AS 1 80 Display any data received from the COM1 port 90 IF LOC 1 THEN PRINT INPUTS LOC 1 1 GOTO 90 100 Transmit key presses to the COM1 port and screen 110KS INKEYS 120PRINT 1 K PRINT K 130GOTO 90 Do it again Enter the program into the computer and run it The example below shows how to test the Serial488A s operation with a Hewlett Packard 7470A plotter Other IEEE plotters are similar but you should refer to the plotter s programming manual for the proper command syntax Notice the Serial488 s front panel LEDs as you type the plotter commands Type the following HPGL output identify command on the keyboard O D The plotter HP 7470A should immediately respond with 7470A By typing the following HPGL command on the keyboard the plotter should respond by retrieving its pen drawing a line and returning the pen SP1 PA1000 1000 PD PA1000 6000 PU SP0 3 6 3 5 Plotter Applications To use the Serial488A to interface an HP IB plotter to a serial computer port you will need the following information about your system Set the Serial488A s internal DIP switches to match the parameters determined The serial data format that the application plotting or graphics program expects the plotter to communicate with These parameters incl
52. poll status byte 4 The internal switch settings for baud rate have been adjusted to include 57600 baud Refer to Section 2 3 for the new switch settings 1 3 Serial488A Serial488A OEM and Serial488 512K Differences 1 The Serial488A and Serial488A OEM utilize a 32 000 character buffer which is dynamically allocated to the serial and IEEE input buffers as required The Serial488 512K utilizes a 512 000 character buffer which is dynamically allocated to the serial and IEEE input buffers as required 2 The Serial488A and Serial488A OEM have the ability to output RS 232 or RS 422 levels The Serial488 512K can only operate at RS 232 levels 3 The Serial488A and Serial488A OEM can operate at selectable baud rates up to 57600 baud The Serial488 512K can operate at selectable baud rates up to 19200 baud 1 4 Available Accessories Additional accessories that can be ordered for the Serial488A include CA 7 1 CA 7 2 CA 7 3 CA 7 4 CA 11 CA 21 CA 22 CA 23 CN 20 CN 22 CN 23 ABC488 Rack488 3 Rack488 4 140 0920 1 5 foot IEEE 488 Cable 6 foot IEEE 488 Cable 6 foot shielded IEEE 488 Cable 6 foot reverse entry IEEE 488 Cable 12 foot IBM PC XT PS2 to Serial488A RS 232 Cable 12 foot Macintosh II SE Plus to Serial488A RS 232 Cable 12 foot Macintosh 512K to Serial488A RS 232 Cable 12 foot IBM AT to Serial488A RS 232 Cable Right Angle IEEE 488 adapter male and female IEEE 488 Multi tap bus strip four female connectors in para
53. s are removed from that buffer and sent to the IEEE bus device The serial terminator s if present are not sent Instead the IEEE terminators are substituted and sent in their place So long as the serial input buffer is not empty the Serial488A will continue to send data from it to the IEEE bus device If the serial input buffer becomes emptied the Seriald88A will command the IEEE bus device to talk if one of the talk back features is enabled This allows the Serial488A to be used as a controller with devices such as plotters or instruments that return status and other information to the host computer When the Serial488A addresses the IEEE bus device to talk it uses the following bus sequence ATN UNL MLA TAG ATN The Serial488A then accepts data from the IEEE device and returns it to the host until the last selected IEEE terminator is detected The IEEE bus terminators are replaced by the serial terminators and these are then sent to the serial host 3 1 If the IEEE device has been addressed to talk but does not respond or finish transmission by the time additional characters are received into the circular serial input buffer the talk sequence will be aborted to allow additional serial information to be sent to the IEEE device 3 2 Serial and IEEE Terminator Substitution The Serial48SA can be configured to provide serial to IEEE 488 and IEEE 488 to serial terminator substitution This is useful when interfacing a serial host w
54. s the Active Talker There can only be one Talker at a time if the information transferred is to be clearly understood by all The act of giving the floor to that device is called Addressing to Talk If the committee chairman can not attend the meeting or if other matters require his attention he can appoint an acting chairman to take control of the proceedings For the GPIB this device becomes the Active Controller At a committee meeting everyone present usually listens This is not the case with the GPIB The Active Controller selects which devices will listen and 5 1 commands all other devices to ignore what is being transmitted A device is instructed to listen by being Addressed to Listen This device is then referred to as an Active Listener Devices which are to ignore the data message are instructed to Unlisten The reason some devices are instructed to Unlisten is quite simple Suppose a college instructor is presenting the day s lesson Each student is told to raise their hand if the instructor has exceeded their ability to keep up while taking notes If a hand is raised the instructor stops his discussion to allow the slower students the time to catch up In this way the instructor is certain that each and every student receives all the information he is trying to present Since there are a lot of students in the classroom this exchange of information can be very slow In fact the rate of information transfer is no faster than
55. switch 2764 35 EPROM 84256 CMOS RAM 6522 VIA 6551 UART Programmed 16L8 PAL 74LS04 LT1081 Schematic U201 U216 U217 U218 U219 U220 U223 U224 U225 U226 U227 U228 U229 U230 U231 U232 Y101 Part Number IC 46 IC 50 IC 14 IC 48 IC 1 IC 34 IC 21 IC 8 IC 3 IC 33 IC 49 IC 5 IC 4 CR 5 TR 4 TR 4E 6 13 Description 256K DRAM 150NS 74LS373 Octal Tri State D 74HCT244 Octal Buffer 74HCT240 Inverting Buffer MC68B09 Microprocessor 74HCTOO Quad NAND 74LS139 Dual Decoder T4LS 138 Decoder TMS9914ANL 74LS04 Hex Inverter 74LS08 Quad AND Gate 75162 IEEE Driver 75160 IEEE Driver 8 000 MHz Crystal Power Supply 115V AC Power Supply 220V AC Sample Programs 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 CLS DUMB TERMINAL PROGRAM FOR THE Serial488A Running under IBM Basica This Program allows direct interaction between the IBM PC and an IEEE bus device through the Serial488A The Serial488A must be configured as the IEEE bus controller and have talk back on terminator enabled Open the serial communications port and set the serial parameters OPEN COMI 9600 n 8 2 cs ds AS 1 Display any characters received from the COMI port IF LOC 1 THEN PRINT INPUT LOC 1 1 Transmit any key presses from keyboard to the COMI port and to the screen K INKEY PRINT 1 K PRINT K GOTO 140 Do it again Al Appendix B Character Codes and IEEE Multil
56. te that it has received data from the serial device The Serial488A and Serial488A OEM can communicate with RS 232 and RS 422 devices by positioning configuration jumpers located within the unit Both devices can communicate at selectable baud rates up to 57600 baud The Serial488 512K can communicate with RS 232 devices at selectable baud rates up to 19200 baud This manual will refer to all three interfaces as the Serial488A Differences between the Serial488A Serial488A OEM and Serial488 512K will be noted where applicable 1 2 Serial488 and Serial488A Differences The Serial488A is both a hardware and firmware upgrade to the Serial488 When issuing product improvements we try to maintain transparent compatibility Occasionally this is not possible You should note the following differences between the two products 1 The Serial488 allocated fixed serial and IEEE input buffers of 4000 characters The Serial488A utilizes a 32 000 character buffer which is dynamically allocated to the serial and IEEE input buffers as required Refer to Section 4 2 for more details 2 The Serial488A has the ability to output RS 232 or RS 422 levels The levels used are internally selectable Refer to Section 2 8 for details 3 As a peripheral the Serial488A s serial poll status byte has been changed to include status of the serial handshake Other minor changes have also been included Refer to Section 4 4 for a complete description of the serial
57. the rate at which the slowest note taker can keep up The instructor though may have a message for one particular student The instructor tells the rest of the class to ignore this message Unlisten and tells it to that one student at a rate which he can understand This information transfer can then happen much quicker because it need not wait for the slowest student The GPIB transfers information in a similar way This method of data transfer is called handshaking More on this later For data transfer on the IEEE 488 the Active Controller must a Unlisten all devices to protect against eavesdroppers b Designate who will talk by addressing a device to talk c Designate all the devices who are to listen by addressing those devices to listen d Indicate to all devices that the data transfer can take place 5 2 To Other Devices Device 1 System Controller Able to Talk Listen and Control Data Bus Device 2 DMM Able to Talk Data Byte and Listen on oo Transfer Control Device 3 Printer Only Able to Listen General Interface Management Device 4 Frequency Counter Only Able to Talk EE DAV IEEE 488 Bus Structure NRFD NDAC i IFC Figure 5 1 AIN SRQ REN EOI 5 3 5 3 SEND IT TO MY ADDRESS In the previous discussion the terms Addressed to Talk and Addressed to Listen were used These terms require some clarification The IEEE 488 standard permits up to 15 devices to be configured w
58. this event check the AC line and the rear panel connection of the power supply for proper Installation If the problem is unresolved refer to the Service Information section of this manual If proper operation is obtained connect an interface cable to the rear of the Serial488A 25 Pin Sub D Connect the other end to the host s serial port Except for connecting IEEE bus instruments the Serial488A is installed and ready to use WARNING The Serial488A makes its earth ground connection through the serial interface cable It should only be connected to IEEE bus devices after being first connected to the host Failure to do so may allow the Serial488A to float to a bus device test voltage This could result in damage to the interface personal injury or death 2 24 Controller Operation 3 1 Controller Mode Serial to IEEE Operation The IEEE Controller mode allows a serial RS 232 or RS 422 host device to send data to a single IEEE bus peripheral or to multiple peripherals if they occupy the same bus address Applications include interfacing a listen only or addressable IEEE printer plotter to a serial printer port Once the Serial488A has initialized itself after power on it waits for serial input data When received it addresses the selected IEEE device to listen with the following bus sequence ATN UNL MTA LAG ATN The data received from the serial host is placed into a circular serial input buffer Simultaneously character
59. tion 2 7 2 3 2 Serial Word Length Selection Data Bits SW1 6 determines the number of data bits often referred to as word length for each serial character transmitted or received The factory default is 8 data bits SW1 View of Serial Word Length Data Bits Selection DOT II OD 8 Data Bits 7 Data Bits 2 3 3 Serial Stop Bit Selection Switch SW1 8 determines the number of stop bits contained in each serial character transmitted and received The factory default is 2 stop bits SW1 View for Serial Stop Bit Selection 1 EET Bit 2 Stop Bits 2 3 4 Serial Parity Selection Serial Parity is selected with S2 6 through 52 8 The Serial488A generates the selected parity during serial transmissions but it does not check parity on data that is received The factory default is parity disabled 2 8 SW2 View for Serial Parity Selection Odd Parity Mark Parity Even Parity Space Parity OPEN DOT lt 12 DL 7 8 BL Parity Disabled 2 3 5 Serial Echo Selection Serial data sent to the Seriald88A will be echoed back to the serial host if SW2 5 is set to the open position Factory default is Echo Disabled SW2 View for Echo Selection DOT Echo Disabled Echo Enabled 2 9 2 3 6 Serial Handshake Selection Switch SW1 5 is used to select between hardware RTS CTS or software Xon Xoff serial handshake control With Xon Xoff the Serial488A issues an Xoff character ASCI
60. to allow additional serial information to be sent to the IEEE device The following is an example of how this feature can be used to communicate with a single IEEE instrument The program example is written in Basic on an IBM PC or compatible and communicates with a Keithley Model 196 DMM 10 20 Example Program using Serial488A with 25 the Talk Back on Terminator Feature Enabled to U j 30 Communicate with a Keithley Model 196 DMM 40 50 Open Basic s serial communications port 60 OPEN COM1 9600 N 8 2 AS 1 70 Set the Model 196 DMM to the 30VDC range 80 PRINT 1 FOR3X The suppresses terminators 90 Request 10 Readings from 196 100 FOR N 1 to 10 110 PRINT 1 Output terminator 120 LINE INPUT 1 AS Get Reading from 196 130 PRINT AS print it on the screen 140 NEXT N 150 END 3 4 3 4 2 Talk Back On Time Out SW2 2 selects whether the Serial488A should address the attached bus device to talk when the Serial488A has no more serial data to send This feature relies on time and not on terminators Its use is primarily for simulating a serial plotter from an IEEE 488 HP IB plotter The factory default is Talk back On Time Out enabled SW2 View for Talk Back on Time Out Selection UU BLU Talk Back on Talk Back on Time Out Disabled Time Out Enabled If Talk Back on Time Out is enabled then Serial488A_ waits approximately 100 milliseconds after it detects its serial input buffer is empty
61. tor Enabled 2 15 2 8 Serial Interface The Serial488A and Serial488A OEM have the ability to output signal levels that are compatible with either RS 232 or RS 422 An internal DIP shorting plug determines which electrical specification is chosen If the interface is to be connected to an IBM PC XT AT PS2 or compatible the RS 232 level should be selected If it will be connected to a Macintosh 512K Plus SE II the RS 422 level should be used For connection to other computers refer to the manufacturer s manual to determine which levels are supported 2 8 1 RS 232 RS 422 Signal Level Selection The Serial488A s and Serial488A OEM s factory default signal levels are compatible with RS 232 To select RS 422 levels carefully remove the 8 position shorting plug with a small flat blade screwdriver from it s socket Install the DIP jumper into the adjacent socket making certain that all of the pins on the shorting plug are inserted correctly The following diagrams show which socket the jumper must be inserted for the desired operation RS 232 Signal Levels Selected Serial488A Shorting Plug 205 o_o ofja olla in nmn nm olla u u 2 2 16 RS 232 Signal Levels Selected Serial488A OEM 901 RS232 4t Shorting Plug SOT DDDDDDDD RS422 CH c DDDDDDDD 2 8 2 Serial Signal Descriptions The Serial488A is equipped with a standard DB 25S connector on its rear panel and requires a standard DB 25P mating
62. ude baud rate word length stop bits parity and serial control Some programs allow these parameters to be selected by the user Other graphics programs depend on the RS 232 version of the plotter defaults Usually Hewlett Packard plotters use 9600 baud 7 data bits 1 stop bit even parity and Xon Xoff serial control Since these plotters are available with serial interfaces the operator s manual of your IEEE plotter should contain this information The IEEE bus address of your plotter This address is usually set by a DIP switch located on the rear of the plotter The first five switches set the address which for Hewlett Packard plotters is usually address 5 Refer to the plotter s operator s manual for exact information above Other parameters which should be selected include L 2 Talk Back on Terminator Enabled Talk Back on Time Out Enabled Serial Terminators set to CR Only IEEE Terminators set to CR Only with EOI enabled 3 7 An IBM PC based Graphics System SerialdaagA The following shows the Serial488A s internal switch settings required to use a Hewlett Packard 7580A plotter with AutoCadTM from AutoDesk on an IBM PC or compatible Because PC and compatibles output RS 232 levels the shorting DIP jumper should be set to the RS 232 position J206 Selecting RS 232 Signal Levels Serial488A iO DOE OO DOE e Co CH Shorting Plug oo000000 RS 422 3 8 Selecting RS 232 Signal Levels Ser
63. vision to the manual As applicable IOtech calibrates its hardware products to published specifications Periodic hardware calibration is not covered under the warranty and must be performed by qualified personnel as specified in this manual Improper calibration procedures may void the warranty Quality Notice IOtech has maintained ISO 9001 certification since 1996 Prior to shipment we thoroughly test our products and review our documentation to assure the highest quality in all aspects In a spirit of continuous improvement IOtech welcomes your suggestions emer Introduction 1 1 Description The Serial488A Serial488A OEM and Serial488 512K Bus Converters provide transparent communication from a serial computer to an IEEE 488 printer plotter or other device They also can be used to control a serial device such as a printer or terminal from an IEEE 488 host computer As a serial to IEEE 488 converter it receives data from a serial host then automatically performs the bus sequences necessary to send this data to the IEEE 488 device If desired data can be requested from the IEEE 488 device and returned to the host As an IEEE 488 to serial converter it functions as a peripheral to an IEEE 488 controller Data received from the controller is sent to the serial device and data received from the serial device is buffered for transmission to the IEEE 488 controller The converter can inform the host by the serial poll status by
64. w this simple procedure Disconnect the power supply from the AC line and from the interface Disconnect any IEEE or serial cables prior to disassembly WARNING Never open the Serial488A case while it is connected to the AC line Failure to observe this warning may result in equipment failure personal injury or death Place the interface upside down on a flat surface Remove the four 4 screws located near the rubber feet Return the interface to the upright position and carefully remove the top cover Modify those parameters which are appropriate for your installation and then carefully re assemble the interface using the reverse of the procedure described 2 3 Serial Port Settings The first parameters to configure are those that correspond to the RS 232 port These include baud rate word length number of stop bits parity selection and type of RS 232 handshake Each of these are described in the following sections 2 3 1 Serial Baud Rate Selection Baud rate defines the number of serial bits per second transferred into and out of the RS 232 interface SWI 1 through SW1 4 determine the serial baud rate The factory default baud rate is 9600 baud Baud rates may be selected from 110 to 57600 baud 110 to 19200 for the Serial488 512K 2 6 Refer to the following diagram for specific baud rates Note on the Serial488 512K selecting 57600 baud will have the same effect as selecting 19200 baud SW View for Serial Baud Rate Selec

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