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Model GPIB-MAC User Manual

1. National Instruments If you enable shadow handshaking the GPIB MAC participates in the data handshake as an Acceptor without actually reading the data It monitors the transfers for the END EOI or end of string character message and holds off subsequent transfers This mechanism allows the GPIB MAC to take control synchronously on a subsequent operation such as cmd or rpp Before performing a gts with a shadow handshake you should call eos to establish the proper end of string character or to disable the EOS detection if the end of string character used by the talker is not known If you call gts with an argument and the GPIB MAC is not CIC the GPIB MAC records the ECIC error Refer also to cac Examples 1 PRINT 1 gts 0 GTS without shadow handshaking 2 PRINT 1 GTS 1 GTS with shadow handshaking 3 PRINT 1 gts What is the standby status response CSB 1 lt CR gt lt LF gt GPIB MAC is in standby status with shadow handshaking 45 SECTION FOUR FUNCTIONS November 1985 National Instruments idMAC Identify System idMAC General Use function Syntax idMAC lt CR gt Purpose You use idMAC if you wish to know the revision level of your software or if you wish to know how much RAM is installed in your GPIB MAC Remarks The identification is returned in three strings The first two strings identify the company product model the software revision level and a copyright notice The third s
2. PROGRAMMING THE GPIB MAC November 1985 National Instruments Serial Port Error Handling The GPIB MAC continuously monitors the serial port for transmis sion errors If it encounters an error in the serial data the GPIB MAC records the error You can program the GPIB MAC to stop processing the programming message when a serial port error Occurs or to ignore these serial port errors Refer to the spign function GPIB Read and Write Termination Method END and EOS You program the GPIB MAC to Talk in order to send data messages over the GPIB and to Listen in order to receive data messages from the GPIB The IEEE 488 specification defines two ways that GPIB Talkers and Listeners may identify the last byte of data messages END and EOS The two methods permit a Talker to send data messages of any length without the Listener s knowing in advance the number of bytes in the transmission END message the Talker asserts the EOI End or Identify signal while the last data byte is being transmitted The Listener stops reading when it detects a data byte accompanied by EOI EOS character the Talker sends an EOS end of string character at the end of its data suing The Listener stops receiving data when it detects the EOS character Either a I bit ASCII character or a full 8 bit binary byte may be used The two methods can be used individually or in combination It is important that the Listener be configured to detect
3. WRT count address list write data data BUS MANAGEMENT FUNCTIONS Function Purpose CLR address list Clear specified device s LOC address list Go to Local TRG address list Trigger selected device s GPIB INITIALIZATION FUNCTIONS Function Purpose CADDR address Change the GPIB address of the GPIB MAC EOS modes eoschar Change disable GPIB EOS termination mode EOT on off Enable disable END message on GPIBwrites ONL on off Place the GPIB MAC online offline RSC on off Request or release System Control TMO values Change or disable time limit SECTION THREE PROGRAMMING THE GPIB MAC November 1985 24 National Instruments SERIAL POLL FUNCTIONS Function RSP address list RSV status byte Purpose Request conduct a serial poll Request service and or set or change the serial poll status byte LOW LEVEL CONTROLLER FUNCTIONS Function CAC mode CMD count commands GTS mode PCT address SIC time SRE on off PARALLEL POLL Function IST on off PPC values PPU address list RPP Purpose Become active controller Send JEEE 488 commands Go from Active Controller to Standby Pass Control Send interface clear Set clear remote enable FUNCTIONS Purpose Set or clear individual status bit for use in GPIB MAC response to Parallel Polls Parallel Poll Configure Parallel Poll Unconfigure Request conduct a Parallel Poll SECTION THREE PROGRAMMING THE GPIB MAC November 1985 National
4. 1 the device will assert DIO line3 which corresponds to 010 in bits O 2 The ppc function sends the device s listen address the Parallel Poll Configure command hex 6A then the Unlisten command The active controller can configure itself to respond to a parallel poll using ppc also This might be used in the case where the GPIB MAC is not the system controller and the system controller does not have the capability to do the configuration Since the GPIB MAC cannot be the controller the GPIB controller in your system must configure the GPIB MAC in order to parallel poll it 118 APPENDIX F PARALLEL POLLING November 1985 National Instruments The Parallel Poll After configuring the device the GPIB MAC now conducts a parallel poll by calling rpp In the previous example where the device was sent a configuration byte of hex 6A if the device s ist bit matches the S bit of hex 6A rpp will return the value 04 Here the third least significant bit is set corresponding to DIO line 3 If any other devices responded positively on other lines those corresponding bits would be set as well Note that the controller may configure more than one device to respond on the same data line in which case the bits in the response byte are set by the ORing of all the responses on that line Disabling Parallel Poll Response The active controller may disable a specific device from responding to a parallel poll by calling ppu with the devic
5. 64 REM Remote state 32 CIC Controller In Charge 16 ATN Attention asserted 8 TACS Talker active 4 LACS Listener active 2 DTAS Device trigger state 1 DCAS Device clear state GPIB ERROR CONDITIONS Numeric Symbolic Value n alue s Description 0 ph NGER No GPIB error condition to report ECIC Command requires GPIB MAC to be CIC ENOL Write detected no listeners EADR GPIB MAC not addressed correctly EARG Invalid argument or arguments ESAC Command requires GPIB MAC to be SC EABO I O operation aborted Reserved ECMD Unrecognized command SECTION FOUR FUNCTIONS November 1985 National Instruments SERIAL PORT ERROR CONDITIONS Numeric Symbolic Value n Value s Description 0 NSER No serial port error condition to report 1 EPAR Serial port parity error 2 EORN Serial port overrun error 3 EOFL Serial port receive buffer overflow 4 EFRM Serial port framing error A detailed description of the conditions under which each bit in status is set or cleared may be found in Appendix B In general the GPIB MAC updates the first three status variables at the end of each programming message It updates the fourth count after a cmd rd or wrt function The errors reported correspond to the previous programming message For example if you call wrt and then stat s any errors returned to you correspond to errors in the wrt programming message not stat However if status is returned in continuous mode t
6. 1 wrt 509497 Write 50 bytes to device at FOR I 1 TO50 primary address 9 and secon PRINT 1 CHR A 1 dary address 97 NEXT I PRINT 1 CHR 13 Send carriage return 2 PRINT 1 wrt 2 Write the data bytes ABCDE PRINT 1 ABCDE at device at address 2 frequently used function 90 SECTION FOUR FUNCTIONS November 1985 O National Instruments xon Change Serial Port XON XOFF Protocol xon Syntax Purpose Remarks Serial Port function xon booltx boolrx CR You use xon at the beginning of your program to configure the GPIB MAC to communicate over the serial port using the same XON XOFF protocol as your Macintosh The argument booltx specifies whether to enable the XON XOFF protocol when sending data out on the serial port If the argument booltx is a 1 the GPIB MAC monitors its serial receive buffer for XON XOFF characters as it sends data over the serial port If it receives the XOFF character decimal 19 or lt ctrl gt s it will immediately stop sending data When it receives the XON character decimal 17 or lt ctrl gt q it begins sending data again If you want to send a data string that may contain a lt ctrl gt s or lt ctrl gt q you must disable booltx The argument boolrx specifies whether to enable the XON XOFF protocol when receiving data over the serial port If the argument boolrx is a 1 and the GPIB MAC is receiving data over the serial port it sends XOFF ove
7. CIC ATN TACS LACS 32 The CIC bit specifies whether the GPIB MAC is the Controller In Charge The CIC bit is set whenever sic is called while the GPIB MAC is System Controller or when another Controller passes control to the GPIB MAC The CIC bit is cleared whenever the GPIB MAC detects Interface Clear IFC from some other device that is System Controller or when the GPIB MAC passes control to another device 16 The ATN bit specifies the state of the GPIB Attention ATN line The ATN bit is set whenever the GPIB ATN line is asserted and cleared when the ATN line is unasserted 8 The TACS bit specifies whether the GPIB MAC has been addressed as a Talker The TACS bit is set whenever the GPIB MAC detects that its talk address and secondary address if enabled has been sent either by the GPIB MAC itself or by another Controller The TACS bit is cleared whenever the GPIB MAC detects the Untalk UNT command a talk address other than its own its own listen address or Interface Clear IX 4 The LACS bit specifies whether the GPIB MAC has been addressed as a Listener The LACS bit is set whenever the GPIB MAC detects that its listen address and secondary address if enabled has been sent either by the GPIB MAC itself or by another Controller The LACS bit is also set whenever the GPIB MAC shadow handshakes as a result of the gts function The LACS bit is cleared whenever the GPIB MAC detects that the Unlisten UNL comm
8. E MTA 65 145 101 e MS A PPE 46 106 70 F MTA 66 146 102 f MS A PPE 47 107 71 G MTA 67 147 103 g MS A PPE 48 110 72 H MTA 68 150 104 h MS A PPE 49 111 73 I MTA 69 151 105 i MS A PPE 4A 112 74 J MTA 6A 152 106 j MS A PPE 4B 113 75 K MTA 6B 153 107 k MS A PPE 4c 114 76 L MTA 6C 154 108 1 MS A PPE 4D 115 7 M MTA 6D 155 100 m MS A PPE 4E 116 78 N MTA 6E 156 110 n MS A PPE 4F 117 79 O MTA 6F 157 111 0 MS A PPE 50 120 80 P MTA 70 160 112 p MS A PPD 51 121 81 Q MTA 1 161 113 q MS A PPD 52 122 82 R MTA 72 162 114 r MS A PPD 53 128 88 S MTA 73 163 115 s MS A PPD 54 124 84 T MTA 74 164 116 t MS A PPD 55 125 85 U MTA 75 165 117 u MS A PPD 56 120 86 V MTA 76 166 118 v MS A PPD 57 127 87 W MTA 77 167 119 w MS A PPD 58 130 88 X MTA 78 170 120 x MS A PPD 59 131 89 Y MTA 79 171 121 y MS A PPD 5A 132 9 Z MTA A 172 122 z MS A PPD 5B 133 91 MTA B 173 123 MS A PPD 5C 134 92 MTA c 174 194 MS A PPD SD 135 93 J MTA D 175 125 MS A PPD SE 136 94 MTA 7E 176 126 MS A PPD SF 137 95 UNT F 177 127 DEL 95 APPENDIX A MULTILINE INTERFACE MESSAGES November 1985 National Instruments Appendix B Status Information This appendix describes the status and error information that the GPIB MAC records as it executes each programming message The number preceding each description is the numeric value of that bit in the status word or of the error code Status Bits The following paragraphs describe the conditions represented by the bits in sta
9. Example PRINT 1 trg 2 10 4 5 7 Trigger 3 devices frequently used function 84 SECTION FOUR FUNCTIONS November 1985 National Instruments wait Wait for Selected Event wait General Use function Syntax wait mask lt CR gt Purpose You use wait to monitor selected GPIB events and to delay any further GPIB MAC activity until one of them Occurs Remarks The argument mask is a numeric string which specifies the events to wait for The numeric string represents a bit mask containing a subset of the same bit assignments as the status word described in the stat function Each bit is set or cleared to wait or not to wait respectively for the corresponding event to occur The numeric string may be expressed as decimal octal or hexadecimal After receiving the wait programming message the GPIB MAC monitors GPIB activity When any event corresponding to the bits set in mask occurs the GPIB MAC returns status information indicating its current status If continuous status reporting has been enabled status will be reported in the format requested If continuous status has not been enabled status will be returned in numeric format You could use wait for example if you wish to wait until a device requests service before you perform a serial poll In this case you send the wait programming message with mask 4096 then wait for status information to be returned You then check that status to see if the SRQI bit is s
10. FOUR FUNCTIONS November 1985 National Instruments 76 Status represents a combination of GPIB MAC conditions Internally in the GPIB MAC status is stored as a 16 bit integer Each bit in the integer represents a single condition A bit value of 1 indicates that the corresponding condition is in effect a bit value of zero indicates that the condition is not in effect Since more than one GPIB MAC condition may exist at one time more than one bit may be set in status The highest order bit of status also called the sign bit is set when the GPIB MAC detects either a GPIB error or a serial port error Consequently when status is negative an error condition exists and when status is positive no error condition exists gpib error represents a single GPIB error condition present serial error represents a single serial error condition present count is the number of bytes transferred over the GPIB by the last rd wrt or cmd function GPIB STATUS CONDITIONS Numeric Symbolic Bit Value n Value s Description 15 32768 ERR Error detected 14 16384 TIMO Timeout 13 8192 END EOI or EOS detected 12 4096 SRQI SRQ detected while CIC 11 2048 Reserved 10 1024 Reserved 9 512 Reserved 8 256 CMPL Operation completed 7 128 LOK Lockout state SECTION FOUR FUNCTIONS November 1985 TI National Instruments GPIB STATUS CONDITIONS CONTINUED Oe NWAUADN Numeric Symbolic Value n Value s Description
11. FSRead refNum amp logEOF s tbox Could not read file continue printf Bytes read into buffer 1dWMn logEOF FSClose refNum don t need input file now 6 send s logEOF refOut DisposPtr s release buffer puts Waiting for any response from device for pause TickCount 30 TickCount lt pause showIn refIn SFGetFile pass where OL 1 typelist OL amp reply S logEOF refOut char s long logEOF Short refOut 130 unsigned short loops 1 puts loops scanf hd amp loops printf Total bytes to send 1d bytes n logEOF loops while loops FSWrite refOut amp logEOF s send file APPENDIX I SERIAL PORT SAMPLE PROGRAM November 1985 National Instruments showiIn refin short refin long count pause char text Read any bytes waiting at the modem port SerGetBuf refin amp count get count if count O text NewPtr count get another buffer if text NULL tbox Port input size too large for memory return printf Number of bytes at input port ld n count if FSRead refin amp count text tbox Can t read input port buffer return write text to screen write 1 text int count for pause TickCount 60 TickCount lt pause else tbox No bytes at input port tbox txt char txt Rect r register long pause SetPort theP
12. GPIB Devices 113 Star Configuration of GPIB Devices xiii TABLE OF CONTENTS November 1985 National Instruments LIST OF TABLES SECTION ONE Introduction 4 Front Panel LEDs SECTION THREE Programming the GPIB MAC 22 Serial Port Characteristics 22 GPIB Characteristics 23 T O Functions 23 Bus Management Functions 23 GPIB Initialization Functions 24 Serial Poll Functions 24 Low level Controller Functions 24 Parallel Poll Functions 25 Serial Port Initialization Functions 25 General Use Functions 25 GPIB MAC Functions SECTION FOUR Functions 39 Data Transfer Termination Methods 76 GPIB Status Conditions 77 GPIB Error Conditions 78 Serial Port Error Conditions 86 Wait Mask Values xiv TABLE OF CONTENTS November 1985 National Instruments Section One Introduction This section provides brief introductions to the GPIB MAC and the IEEE 488 It also describes the physical electrical and environmental characteristics of the GPIB MAC Introduction to the GPIB MAC The GPIB MAC is a high performance GPIB to Macintosh interface The GPIB MAC together with a Macintosh personal computer provide a means of Controlling Talking and Listening on the GPIB The GPIB MAC has all the software and logic required to implement the physical and electrical specifications of the IEEE 488 It is capable of interpreting and executing high level commands that you send to it over the Macintosh serial port Introduction to
13. GPIB MAC More detailed configuration information is included in Section Two The Model GPIB MAC Front Panel The front panel of the GPIB MAC is shown in the following figure The six light emitting diodes LEDs show the current status of the GPIB MAC NATIONAL Pi GPIB MAC IEEE 488 MAC POWER READY TALK LISTEN e o o e Front Panel of the GPIB MAC 3 SECTION ONE INTRODUCTION November 1985 National Instruments The following table shows what each LED indicates when lit LED Purpose POWER indicates power is on READY indicates that the power on self test has passed successfully and unit is ready to operate TALK indicates that the GPIB MAC is currently addressed to Talk on the GPIB LISTEN indicates that the GPIB MAC is currently addressed to Listen on the GPIB ATN indicates that the GPIB signal line ATN is asserted low SRQ indicates that the GPIB signal line SRQ is asserted low Ihe Model GPIB MAC Back Panel The back panel of the GPIB MAC is shown in the following figure The power connector 9 position configuration switch 9 pin D subminiature connector and GPIB IEEE 488 port are shown 4 SECTION ONE INTRODUCTION November 1985 National Instruments Power GPIB IREE 488 Connector Port 9 pin 9 position D subminiature Configuration Connector Switch Back Panel of the Model GPIB MAC 5 SECTION ONE INTRODUCTION November 1985 National Instruments Mechanical Specifica
14. GPIB MAC returns to you the current eos settings The assignment made by this function remains in effect until you call eos again call onl or you turn off the GPIB MAC Refer to the GPIB Read and Write Termination explanation in Section Three 40 SECTION FOUR FUNCTIONS November 1985 National Instruments Examples 1 PRINT 1 eos R B 10 Terminate read when lt LF gt is detected compare all 8 bits do not send EOI with lt LF gt PRINT 1 rd 10 5 Read 10 bytes from device 5 into serial port buffer RESP INPUTS 10 1 Input 10 bytes from serial port buffer LINE INPUT 41 COUNT Input string that indicates number CNT V AL COUNTS of bytes actually read from GPIB PRINT COUNTS bytes were read from GPIB Print number of bytes that were read from the GPIB 2 PRINT 1 EOS X 13 Tell GPIB MAC on wrt send EOI with CR on rd do not terminate when CR is detected compare 7 bits PRINT 41 wrt 10 5 GPIB MAC sends EOI with CR CHR 13 to tell listeners that this is the last byte of data PRINT 41 012345678 X CHR 13 3 PRINT 1 eos What are the current EOS settings response X 13 lt CR gt lt LF gt 41 SECTION FOUR FUNCTIONS November 1985 National Instruments eot Enable Disable END Message on GPIB Writes eot Syntax Purpose Remarks Initialization function eot bool CR You use eot at the beginning of
15. Instruments Serial Port Functions SERIAL PORT INITIALIZATION FUNCTIONS Function Purpose ECHO on off Echo characters received from serial port SPIGN on off Ignore serial port errors XON modes Change serial port XON XOFF protocol General Use Functions GENERAL USE FUNCTIONS Function Purpose IDMAC Identify system STAT modes Return GPIB MAC status WAIT mask Wait for selected event List of Functions in Alphabetical Order The following is an alphabetical list of all functions GPIB MAC FUNCTIONS Function Purpose CAC mode Become active controller CADDR address Change GPIB address of the GPIB MAC CLR address list Clear specified device s CMD count Send GPIB commands commands ECHO on off Echo characters received from serial port 25 SECTION THREE PROGRAMMING THE GPIB MAC November 1985 National Instruments GPIB MAC FUNCTIONS CONTINUED EOS modes eos EOT on off GTS mode IDMAC IST set clear LOC address list ONL on off PCT address PPC values PPU address list RD count address RPP RSC on off RSP address list RSV serial poll SIC time SPIGN on off SRE on off STAT modes TMO values TRG address list WAIT mask WRT count address list data XON modes Change disable GPIB EOS termination mode Enable disable END message on GPIB writes Go from Active Controller to Standby Identify system Set or clear individual status bit for use in GPIB MAC response to Parallel Pol
16. NSER 5 SECTION FOUR FUNCTIONS November 1985 National Instruments tmo Change or Disable Time Limit tmo Initialization function Syntax Purpose tmo timeio timesp CR You use tmo at the beginning of your program to change the time limits in effect on the GPIB MAC The time limits prevent the GPIB MAC from hanging indefinitely when an error situation prevents normal completion of an operation Remarks The arguments timeio and timesp are numeric strings timeio specifies the amount of time in seconds the GPIB MAC waits for an I O operation rd wrt cmd or the wait function to complete timesp specifies the amount of time in seconds each device is given in which to respond to a serial poll The power on timeouts are 10 seconds for timeio and 1 10 of a second for timesp timeio and timesp may be any decimal number between 00001 and 3600 which corresponds to time limits between 10 microseconds and 1 hour 10 1 specifies a time of 10 seconds for I O operations and 1 10 of a second for serial poll response timeio and timesp may also be 0 which disables either timeout accordingly Neither timeio nor timesp may contain commas e g 1000 is correct but 1 000 is not The timeio time limit is in effect for the cmd rd and wrt functions If the GPIB MAC cannot complete any of these functions within the period of time set by timeio it aborts the function and records the EABO error Bytes that were transfe
17. PRINT 1 stat n Get GPIB MAC status REM GPIB MAC responds with REM 340 lt CR gt lt LF gt 0 lt CR gt lt LF gt 0 lt CR gt lt LF gt 0 lt CR gt lt LF gt REM Now read status into variables STATUS VAL LINE INPUT 1 STATUS LINE INPUT 1 GPIBERR LINE INPUT 1 SPERR LINE INPUT 1 COUNT REM Go to error routine at 500 if error occurred IF STATUS lt 0 THEN GOTO 500 REM Go to SRQ service routine if SRQ is asserted IF STATUS AND amp H1000 THEN GOTO 400 REM REM Place code here to service SRQ REM REM Print gpib error and serial error values to REM determine what errors occurred PRINT GPIB error GPIBERR PRINT Serial error SPERR STOP SECTIONFOUR FUNCTIONS November 1985 National Instruments 2 80 10 PRINT 1 stat s 20 REM If it has just read 3 bytes from the GPIB 30 REM GPIB MAC responds with 40 REM CMPL REM ATN LACS lt CR gt lt LF gt NGER lt CR gt lt LF gt 50 REM NSER lt CR gt lt LF gt 3 lt CR gt lt LF gt The following list illustrates what appears on the screen when you are programming the GPIB MAC from a terminal Programming messages you enter are in normal type GPIB MAC responses are in bold The statements in parentheses are comments stat c Sn enable continuous status reporting 344 8 3 CMPL REM ATN TACS status returned NGER NSER 3 wrt 10 ABCDE Write the string ABCDE 344 device 10 Status returned 5 CMPL REM ATN TACS NGER
18. argument bool is 1 the GPIB MAC takes control immediately that is it takes control asynchronously If the argument bool is 0 the GPIB MAC takes control after any handshake that is in progress completes that is it takes control synchronously If you call cac without an argument the GPIB MAC returns to you the current controller status which is 0 if the GPIB MAC is not the Active Controller and1 if the GPIB MAC ig the Active Controller If call cac with an argument and the GPIB MAC is not CIC the GPIB MAC records the ECIC error The power on Controller status of the GPIB MAC is Idle Controller Refer also to gts and sic 29 SECTION FOUR FUNCTIONS November 1985 National Instruments Examples 1 PRINT 1 cac 1 Take control immediately 2 PRINT 4 1 cacO Take control synchronously 3 PRINT 1 CAC Are we the active controller response 1 lt CR gt lt LF gt yes we re CAC 30 SECTION FOUR FUNCTIONS November caddr caddr Syntax Purpose Remarks 1985 National Instruments Change GPIB Address of the GPIB MAC Initialization function caddr addr CR You use caddr at the beginning of your program to change the GPIB address of the GPIB MAC The argument addr is a device address that specifies the new GPIB address for the GPIB MAC addr consists of a primary address and an optional secondary address The secondary address is separated from the primary address by a plus s
19. bits and 2 stop bits from within Microsoft BASIC place the following BASIC statement at the beginning of your program OPEN COM1 57600 N 8 2 AS 1 121 APPENDIX G SETTING SWITCHES November 1985 National Instruments then set the switches on the GPIB MAC as follows o 12 34 5 67 8 9 Remember whatever serial port characteristics you decide to use you must set up both your Macintosh and your GPIB MAC to the exact same characteristics 122 APPENDIX G SETTING SWITCHES November 1985 National Instruments Appendix H Sample Program This appendix contains general programming steps and a sample program These are meant to be guides for you as you start writing your programs for the GPIB MAC General Steps The steps below are general programming steps The following pages contain explanations of these steps and show a sample program Step 1 Send stat function to have status information returned to you after your programming message step 2 Send serial port initialization functions if you need to change default serial port settings step 3 Send GPIB initialization functions if you need to change default GPIB settings step 4 Communicate with the device using the rd and wrt functions and check status if you requested it After you initialize the GPIB MAC the rd and wrt functions may be the only functions you will need Using an HP 7475A Plotter with a Macintosh This example shows how to write a program on
20. command is the ASCII character underscore _ Refer to Example 2 to learn how to send non printable characters If you call cmd without count the GPIB MAC recognizes the end of the command string when it sees a CR or lt LF gt count is required only if the command string contains a CR or an LF character However a CR or an lt LF gt in the command string would be unusual since neither of these is a defmed GPIB command 35 SECTION FOUR FUNCTIONS November 1985 National Instruments The GPIB commands or interface messages are listed in Appendix A They include device talk and listen addresses secondary addresses messages device clear and trigger instructions and other management messages Do not use cmd to send programming instructions to devices Use rd and wrt to send or receive device programming instructions and other device dependent information The cmd operation terminates when the GPIB MAC successfully transfers all commands the GPIB MAC detects an error GPIB MAC is not CIC the I O time limit is exceeded the Take Control TCT command is in your command string and is sent to the GPIB the Interface Clear IFC message is received from System Controller not the GPIB MAC After cmd terminates the GPIB MAC records the number of command bytes it actually sent If an event in the above list occurs the count may be less than expected If you specify count and enter
21. during that call The END bit is cleared in the status word at the start of any subsequent programming message 4096 The SRQI bit specifies whether a device is requesting service This bit is set in the status word whenever the SRQ line is asserted The bit is cleared whenever the GPIB SRQ line is unasserted CMPL 256 LOK REM The CMPL bit specifies that the operation relating to this status information is complete This bit is always set and is useful in identifying the status word from other responses 128 The LOK bit specifies whether the GPIB MAC is in a lockout state The LOK bit is set whenever the GPIB MAC detects the Local Lockout LLO message has been sent either by the GPIB MAC or by another Controller The LOK bit is cleared when the Remote Enable REN GPIB line becomes unasserted either by the GPIB MAC or by another Controller 64 The REM bit specifies whether the GPIB MAC is in remote state The REM bit is set whenever the Remote Enable REN GPIB line is asserted and the GPIB MAC detects its listen address has been sent either by the GPIB MAC or by another Controller The REM bit is cleared whenever REN becomes unasserted or when the GPIB MAC as a Listener detects the Go to Local GTL command has been sent either by the GPIB MAC or by another Controller or when the LOC function is called while the LOK bit is cleared in status 98 APPENDIX B STATUS INFORMATION November 1985 National Instruments
22. is 64 and the secondary address is 2 or 98 which are equivalent 0 2 or 04 98 or 324 98 or 0 x62 pct passes CIC authority from the GPIB MAC to the device specified by addr The GPIB MAC auto matically goes to Controller Idle State It is assumed that the target device has Controller capability If you call pct with an argument and the GPIB MAC is not CIC it records the ECIC error If you call pet without an argument the GPIB MAC records the EARG error 52 SECTIONFOUR FUNCTIONS November 1985 National Instruments Example PRINT 1 pct 7 18 Pass control to device with primary address 7 and secondary address 18 53 SECTIONFOUR FUNCTIONS November 1985 National Instruments ppc Parallel Poll Configure ppc Syntax Purpose Remarks Parallel Poll function ppc addr ppr s addr ppr s addr ppr s lt CR gt You use ppc to configure specified devices to respond to parallel polls in a certain manner addr specifies the GPIB address of the device to be enabled or disabled for parallel polls addr consists of a primary address and an optional secondary address The secondary address is separated from the primary address by a plus sign Both addresses are expressed as numeric strings Only the lower five bits of each address are significant These bits may be in the range from 0 through 30 for both the primary and the secondary address Therefore the binary value 01100010 decimal 98 i
23. more than count command bytes the excess command bytes up to the lt CR gt lt LF gt are discarded If you call cmd and the GPIB MAC is not CIC the GPIB MAC records the ECIC error 36 SECTION FOUR FUNCTIONS November 1985 National Instruments If the GPIB MAC is CIC but not Active Controller it takes control and asserts ATN before sending the command bytes It remains Active Controller afterward Refer to Appendix A to convert hex values to ASCII characters Examples 1 PRINT 1 CMD Program device at address 11 to listen and GPIB MAC at address 0 to talk PRINT 1 Device listen address is 43 or ASCII and GPIB MAC talk address is 64 or ASCII PRINT 1 WRT Write the string ABCDE to PRINT 1 ABCDE device at address 11 2 PRINT 1 cmd CHR 13 W CHR 9 Pass control to device 23 CHR 9 TCT command 37 SECTION FOUR FUNCTIONS November 1985 National Instruments echo Echo Characters Received from Serial Port echo Serial Port function Syntax echo bool lt CR gt Purpose You use echo when a terminal emulation program is run on the Macintosh while connected to the GPIB MAC and you wish to echo what you type on the screen Remarks If the argument bool is 1 characters received from the serial port are echoed back to the serial port If the argument bool is 0 characters are not echoed If the argument bool is 1 and echoing was previously disabled cha
24. of 8 bit characters which are transferred without any translation to the GPIB The argument alist is a list of addrs separated by commas or spaces addrs are addresses that specify the GPIB addresses of the Listener or Listeners if more than one address is given A device address consists of a primary address and an optional secondary address The secondary address is separated from the primary address by a plus sign Only the lower five bits of each address are significant These bits may be in the range from 0 through 30 for both the primary and the secondary address Therefore the binary value 01100010 decimal 98 is interpreted as decimal 2 The following examples all specify a primary address of 0 and a secondary address of 2 The listen address is 32 the talk address is 64 and the secondary address is 2 or 98 which are equivalent 0 2 or 0498 or 32498 or 0 x62 88 SECTION FOUR FUNCTIONS November 1985 National Instruments When count is not specified the GPIB MAC recognizes the end of the data string when it sees a carriage return or a line feed count is required when your data string contains embedded carriage return or linefeed characters If you specify an address list the GPIB MAC must be CIC to perform the addressing If this is the first function you call that requires GPIB controller capability and you have not disabled System Controller capability with rsc the GPIB MAC sends Interface Clea
25. spign at the beginning of your program if you wish to change the effect that serial port errors have on how the GPIB MAC processes programming messages and data This function tells the GPIB MAC to ignore or not to ignore the occurrence of serial port errors By default the GPIB MAC ignores serial port errors If the argument bool is 0 the GPIB MAC will not ignore serial port errors When bool is 0 the GPIB MAC does not execute programming messages that con tain serial port errors A list of serial port errors are listed in Appendix B Also if a serial port error occurs with any byte contained in a cmd or wrt data string the GPIB MAC discards that data byte and all remaining bytes in the string The serial port errors include parity overrun framing and overflow errors If the argument bool is 1 the GPIB MAC executes all programming messages and sends all data even if serial port errors occur as the messages and data bytes are received No matter what value bool has the GPIB MAC still records the errors in the serial error portion of the status area If you call spign without an argument the GPIB MAC returns to you the current setting Refer also to cmd and wrt 71 SECTION FOUR FUNCTIONS November 1985 National Instruments Examples 1 PRINT 1 spign 0 Do not execute programming messages or process data that contain serial port errors 2 PRINT 1 spign 1 Execute all programming messages
26. the IEEE 488 GPIB The IEEE 488 also known as the General Purpose Interface Bus or GPIB is a high speed parallel bus structure originally designed by Hewlett Packard It is generally used to connect and control programmable instruments but has gained popularity in other applications such as intercomputer communication and peripheral control The specifications of the GPIB are too lengthy and comprehensive to be explained in this manual However Appendix D Operation of the GPIB contains a summary of pertinent IEEE 488 information you might find useful Description of the Model GPIB MAC Included here are the GPIB MAC environmental physical and electrical specifications 1 SECTION ONE INTRODUCTION November 1985 National Instruments Environmental Specifications The GPIB MAC is designed to operate in temperatures ranging from 10 to 40 degrees Celsius and in humidity ranging from 10 to 95 non condensing The GPIB MAC can be stored in temperatures ranging from 0 to 70 degrees Celsius Physical Specifications The GPIB MAC shown in the following figure is housed in a structural foam injection molded case The unit can be rack mounted or placed on a table Model GPIB MAC 2 SECTION ONE INTRODUCTION November 1985 National Instruments Quick Reference Chart On the back panel of the GPIB MAC is a reference chart that contains the information you need to configure the rear panel switches of the
27. use parity and the other side does 104 APPENDIX B STATUS INFORMATION November 1985 National Instruments Appendix C Changing from 115 Volts AC to 230 Volts AC This section shows you how to convert your GPIB MAC from 115 Volts AC to 230 Volts AC 1 Tum the power switch to Off This switch is located on the rear panel of the GPIB MAC 2 Disconnect the power cord from the power source and from the rear panel of the GPIB MAC 3 Remove the cover from the GPIB MAC by first removing the two screws on both sides of the housing Lift off the cover 4 Change the setting of the red power selector switch so that it reads 230V The following figure shows the location of the power selector switch Power Selector Switch GPIB MAC with Cover Removed 105 APPENDIX C CHANGING FROM 115 Volts AC TO 230 Volts AC November 1985 National Instruments 3s 106 Replace the cover Be sure the aluminum side plates are in the proper place Replace the screws you removed in Step 1 Remove the fuse assembly Replace the 1 4 ampere fuse supplied with the GPIB MAC with a 1 8 ampere fuse Re insert the fuse assembly APPENDIX C CHANGING FROM 115 Volts AC TO 230 Volts AC November 1985 National Instruments Appendix D Operation of the GPIB The GPIB is a link or bus or interface system through which interconnected electronic devices communicate Hewlett Packard invented the GPIB which they call the HP IB to conn
28. your program if you wish to change how the GPIB MAC terminates GPIB writes Using eot you tell the GPIB MAC to auto matically send or not send the GPIB END message with the last byte that it writes to the GPIB If the argument bool is 1 the GPIB MAC automatically sends the END message with the last byte of each wrt If the argument bool is 0 END is not sent The power on default is 1 If you call eot without an argument the GPIB MAC returns to you a 1 to indicate END termination is currently enabled or a O to indicate END termination is currently disabled The assignment made by eot remains in effect until you call eot again call onl or you turn off the GPIB MAC The GPIB MAC sends the END message by asserting the GPIB EOI signal during the last byte of a data transfer eot is used primarily to send variable length data Refer to the GPIB Read and Write Termination explanation in Section Three 42 SECTION FOUR FUNCTIONS November 1985 National Instruments Examples 1 PRINT 1 eot O Disable END termination 2 PRINT 1 EOT 1 Send END with last byte PRINT 1 WRT 3 Write data to device at address 3 PRINT 1 ABCDE The EOI line is automatically asserted when the last byte the letter E is sent to tell the Listeners it is the last byte of data 3 PRINT 1 eot What is the current EOT setting response 1 lt CR gt lt LF gt END termination is currently enabled 43 SECTION FOU
29. 0 microseconds The action of asserting IFC for at least 100 microseconds initializes the GPIB and makes the interface board become CIC When needed sic is generally used at the beginning of a program to make the GPIB MAC CIC and is used when a bus fault condition is suspected The IFC signal resets only the GPIB interface functions of bus devices and not the internal device functions Device functions are reset with the clr programming message To determine the effect of these messages consult the device documentation If you are in a debugging environment you may want to vary the amount of time IFC is asserted For example you may set time to 10 seconds to allow you to check on a bus analyzer that IFC is actually being asserted Otherwise you do not need to include the time argument 69 SECTION FOUR FUNCTIONS November 1985 National Instruments The GPIB MAC records the ESAC error if you have disabled its System Controller capability with the rsc function It records the EARG error if you specify a time outside the range 0001 to 3600 Refer also to clr and to Appendix D Examples 1 PRINT 1 sic Send interface clear for 500 microseconds 2 PRINT 1 SIC 01 Send interface clear for 10 milliseconds 710 SECTION FOUR FUNCTIONS November 1985 National Instruments spign Ignore Serial Port Errors spign Serial Port function Syntax spign bool lt CR gt Purpose Remarks You use
30. 10 Then I used LINE INPUT to read the response byte and got nothing but a carriage return and linefeed as a response Am I doing something wrong Answer No To conduct a serial poll the GPIB MAC must be Controller In Charge or it must be able to become Controller In Charge If the GPIB MAC cannot become Controller In Charge no serial poll is conducted and therefore you will not get a response string To see if this is the problem ask for status see stat and check to see if the ECIC error occurred If it did you have passed control or system controller authority to some other GPIB device and will not be able to perform a serial poll until the GPIB MAC gets controller authority back 116 APPENDIX E COMMON QUESTIONS November 1985 National Instruments Appendix F Parallel Polling A Parallel Poll allows a GPIB controller to obtain information from several devices on the GPIB in one operation The controller polls configured devices and reads back a single response byte that contains one bit of information from each device From this information the controller can determine which devices need servicing Operation A device is configured by sending it its listen address and a parallel poll enable PPE message There are 16 possible PPE messages hex 60 hex 6F The bits in the PPE message have the following meaning U S DIOtines 1 8 0 11 IiIXIXIXXX U when 0 hex 6X parallel poll is enabled when 1 h
31. 7 or 8 bit data Example of a Programming Message with Data String The following lines of BASIC code PRINT 1 wrt 2 PRINT 1 IN CL contain the function name wrt the argument 2 and the data string IN CI This programming message is telling the GPIB MAC to write to the device at primary address 2 IN CL is the data string which contains the data wrt will send out on the GPIB In this case a CR is automatically sent by BASIC following each print string so again it is not necessary to include it here How Messages are Processed The GPIB MAC processes a programming message on a line by line basis The GPIB MAC buffers the entire message interprets the function name and arguments then executes the message The data portions of the wrt and cmd functions are not processed on a line by line basis The data immediately following a wrt and a cmd are sent directly to the GPIB Function Names The function names have been selected to indicate each function s purpose thereby making your programs easy to understand However if you wish to reduce some overhead in your program and do not mind giving up these advantages you may use only as much of the function name as is necessary to distinguish it from other functions This abbreviated form of the function name is shown in boldface in the function tables and in the syntax portions of the function descriptions 18 SECTION THREE PROGRAMMING THE GPIB MAC November 1
32. 985 National Instruments For example the wait function may be called using either of the next two statements PRINT 1 wait x5000 PRINT 1 wa x5000 Function Argument Delimiters When you type in a function separate the first argument from the function name with at least one space Separate each additional argument with at least one space or a comma In the syntax portions of the function descriptions in Section Four the square brackets are optional If you want to include optional information you do not need to type the brackets only the information inside the brackets Abbreviations for Arguments The function descriptions in Section Four use abbreviations for some arguments They are as follows addr a GPIB address alist one or more addrs bool a boolean value 1 true on or enable 0 false off or disable GPIB Address Each device on the GPIB has a GPIB address The GPIB MAC s address is 0 at power on and may be changed using the caddr function Refer to the manuals of your GPIB devices to learn their addresses You will need to know these when you begin to program the GPIB MAC Only the lower five bits of each GPIB address are significant These bits may be in the range from 0 through 30 for both the primary and the secondary address For example the binary value 01100010 decimal 98 is interpreted as decimal 2 19 SECTION THREE PROGRAMMING THE GPIB MAC November 1985 National Instru
33. 985 National Instruments Step 2 Serial Port Functions Send serial port initialization programming messages if necessary You can skip this for this example Step3 GPIB Initialization Functions Send GPIB initialization programming messages if necessary Again you can skip this for this example Step4 Communicate with rd and wrt Functions Communicate with the device using wrt programming messages and reading back status after each Here is the heart of the program After each wrt string call the subroutine status which will check for errors The plotter s GPIB address is 5 PRINT 1 wrt 5 PRINT 4 1 in sp1 pa1000 3000 c1500 GOSUB status status STAT VAL LINE INPUT 1 status LINE INPUT 1 gpiberr LINE INPUT 1 sperr LINE INPUT 1 cnt PRINT status gpiberr sperr cnt if stat 0 GOSUB error Following is the completed program OPEN com1 9600 n 8 1 AS 1 PRINT 1 stat c n GOSUB status PRINT 1 wrt 5 PRINT 1 in sp1 pa1000 3000 ci500 GOSUB status END 125 APPENDIX H SAMPLE PROGRAM November 1985 National Instruments status STAT VAL LINE INPUT 1 status LINE INPUT 1 gpiberr LINE INPUT 1 sperr LINE INPUT 1 cnt PRINT status gpiberr sperr cnt if stat 0 GOSUB error error REM Place your code to handle errors here STOP 126 APPENDIX H SAMPLE PROGRAM November 1985 National Instruments Appendix I Serial Port Sample Prog
34. ABO 6 The GPIB MAC records this error when I O has been cancelled By far the most common cause of this error is a timeout condition 102 APPENDIX B STATUS INFORMATION November 1985 National Instruments To remedy a timeout error if I O is actually progressing but times out anyway lengthen the timeout period with tmo More frequently however the I O is stuck the Listener is not continuing to handshake or the Talker has stopped talking or the byte count in the call which timed out was more than the other device was expecting Be sure that both parties to the transfer understand what byte count is expected or if possible have the Talker use the END message to assist in early termination ECMD 17 The GPIB MAC records this error when your programming message received by the GPIB MAC does not contain a recognizable function name This can happen if the function name is misspelled or if a transmission error occurred that resulted in the function name being corrupted Check your function name spelling and check serial error to see if a serial port error has been posted Serial Port Error Codes The following paragraphs describe the serial port errors in detail When a serial port error occurs as the GPIB MAC receives a programming message the GPIB MAC posts the error and discards the message If a serial port error occurs in the middle of a data stream following a cmd or wrt function the GPIB MAC discards that data byte and
35. AC online allows the GPIB MAC to communicate over the GPIB and also restores all GPIB MAC settings to their power on values Refer to the Serial Port Characteristics table and the GPIB Characteristics table in Section Three for the GPIB MAC power on settings 50 SECTION FOUR FUNCTIONS November 1985 National Instruments Examples 1 PRINT 1 onl 1 Put the GPIB MAC online and restore its power on settings 2 PRINT 1 ONL 0 Put the GPIB MAC offline to prevent it from communicating with the GPIB 51 SECTION FOUR FUNCTIONS November 1985 National Instruments pct Pass Control pct Specialized Controller function Syntax Purpose Remarks pct addr lt CR gt You use pet to pass Controller In Charge CIC authority from the GPIB MAC to some other device The argument addr is the address of the device you wish you wish to pass control to addr consists of a primary address and an optional address The secondary address is separated from the primary address by a plus sign Both address are expressed as numeric strings Only the lower five bits of each address are significant These bits may be in the range from 0 through 30 for both the primary and the secondary address Therefore the binary value 01100010 decimal 98 is interpreted as decimal 2 The following examples all specify a primary address of 0 and a secondary address of 2 The listen address is 32 the talk address
36. ATION November 1985 National Instruments NGER 0 ECIC ENOL The GPIB MAC reports this error when GPIB MAC detected no GPIB errors during the last operation l The GPIB MAC records this error when you call a function that requires that the GPIB MAC be CIC and it is not CIC In cases when the GPIB MAC should always be the Controller In Charge the remedy is to be sure to call sic to send Interface Clear before attempting any of these calls and to avoid sending the command byte TCT hex 09 Take Control In multiple Controller In Charge situations the remedy is to always be certain that the CIC bit appears in status before attempting these calls If it is not you may call wait 32 to wait to become CIC and to delay further processing until control is passed to the GPIB MAC 2 The most common cause of this error is that the GPIB MAC attempted to write to the GPIB when no listeners were addressed The remedy is to be sure that the proper listen address is in the alist argument string to use cmd to properly address the listeners or to be sure some other controller has addressed the listeners before you call wrt This error may occur more rarely in situations in which the GPIB MAC is not the Controller In Charge and the Controller asserts ATN before the write call in progress has ended The remedy is either to reduce the write byte count to that which is expected by the Controller or to resolve the situation on the Control
37. FUNCTIONS November 1985 National Instruments If this is the first function you call that requires GPIB controller capability and you have not disabled System Controller capability with rsc the GPIB MAC sends Interface Clear IFC to make itself CIC It also asserts Remote Enable If you passed control to some other GPIB device control must be passed back to you or you must send IFC to make yourself CIC before making this call Otherwise the ECIC error will be posted If the GPIB MAC is not CIC and you do not specify the talker address the GPIB MAC assumes it will be addressed by the Controller then proceeds If you call rd without an argument the GPIB MAC records the EARG error Refer also to tmo Example PRINT 1 rd 10 3 Read up to 10 bytes from the GPIB device at address 3 RESP INPUT 10 1 Input 10 bytes from serial port buffer LINE INPUT 1 COUNT Input ASCII string representing number of bytes read from the GPIB COUNT VAL COUNT COUNT is number of bytes read from GPIB remaining bytes in RESP may be ignored frequently used function 60 SECTION FOUR FUNCTIONS November 1985 National Instruments rpp Request Conduct a Parallel Poll rpp Parallel Poll function Syntax Purpose Remarks rpp lt CR gt You use rpp if you wish to conduct a parallel poll to obtain information from several devices at the same time rpp causes the GPIB MAC to con
38. GPIB Signals 110 Data Lines 110 Handshake Lines 111 Interface Management Lines 111 Physical and Electrical Characteristics 114 Configuration Restrictions 115 APPENDIX E Common Questions 117 APPENDIX F Parallel Polling 117 Operation 118 Configuration 119 The Parallel Poll 119 Disabling Parallel Poll Response 119 Example 121 APPENDIX G Setting Switches 123 APPENDIX H Sample Program 123 General Steps 123 Using an HP 7475A Plotter with a Macintosh 123 Getting Ready to Program Xi TABLE OF CONTENTS November 1985 National Instruments 124 Programming Steps 124 Step 1 stat Function 125 Step 2 Serial Port Functions 125 Step 3 GPIB Initialization Functions 125 Step 4 Communicate with rd and wrt Functions 127 APPENDIX I Serial Port Sample Program xi TABLE OF CONTENTS November 1985 National Instruments LIST OF FIGURES SECTION ONE Introduction 2 Model GPIB MAC 3 Front Panel of the GPIB MAC 5 Back Panel of the Model GPIB MAC SECTION TWO Installation and Configuration 8 GPIB MAC DIP Switch 8 Factory Use Only 9 T bit Word Length 9 8 bit Word Length 10 1 Stop Bit 10 2 Stop Bits 11 Configuration for Parity Types 12 Baud Rate Settings 14 GPIB MAC with Serial Cable Power Cable and GPIB Cable APPENDIX C Changing from 115 Volts AC to 230 Volts AC 105 GPIB MAC with Cover Removed APPENDIX D Operation of the GPIB 109 GPIB Cable Connector 112 Linear Configuration of
39. II character For example 10 represents the ASCII linefeed character DATA TRANSFER TERMINATION METHODS Description Letter REOS terminate read when EOS is detected R XEOS set EOI with EOS on write functions X BIN compare all 8 bits of EOS byte rather than B low 7 bits all read and write functions DISABLE disable all eos modes D 39 SECTIONFOUR FUNCTIONS November 1985 National Instruments Methods R and B determine how GPIB read operations performed by the GPIB MAC terminate If Method R alone is chosen reads terminate when the low 7 bits of the byte that is read match the low 7 bits of the EOS character If Methods R and B are chosen a full 8 bit comparison is used Methods X and B together determine when GPIB write operations performed by the GPIB MAC send the END message If Method X alone is chosen the END message is sent automatically with the EOS byte when the low 7 bits of that byte match the low 7 bits of the EOS character If Methods X and B are chosen a full 8 bit comparison is used Note that defining an EOS byte for the GPIB MAC does not cause the GPIB MAC to insert that byte into the data string when performing GPIB writes To send the EOS byte you must include it in the data string that you send following the wrt programming message By default no eos modes are enabled If you call eos with B alone as an argument the GPIB MAC records the EARG error If you call eos without an argument the
40. Instruments Section Three Programming the GPIB MAC This section shows how to program the GPIB MAC by using programming messages and data strings It describes programming messages their format and how they areprocessed along with the functions and function arguments that make up the programming messages Programming Messages You program the GPIB MAC by sending it programming messages which are ASCII strings and data strings by way of its serial port Programming Message Format A programming message consists of a function name one or more arguments optional followed by a carriage return CR a linefeed lt LF gt or a carriage return followed by a linefeed lt CR gt lt LF gt You may enter programming messages in any combination of uppercase and lowercase letters Example of a Programming Message The following line of BASIC code PRINT 1 clr 3 4 contains the function name clr and the arguments 3 and 4 This programming message tells the GPIB MAC to clear the devices at GPIB addresses 3 and 4 PRINT 1 is the BASIC command to send characters to the serial port after the serial port has been opened with the OPEN COM statement In this example BASIC automatically sends a lt CR gt so it is not necessary to include it here 17 SECTION THREE PROGRAMMING THE GPIB MAC November 1985 National Instruments The cmd and wrt programming messages are followed by a data string which may contain
41. Instruments Apple and Macintosh are trademarks of Apple Computer Inc Microsoft is a registered trademark of Microsoft Corporation FCC RADIO FREQUENCY INTERFERENCE COMPLIANCE This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instruction manual may cause interference to radio communica tions It has been tested using a shielded serial I O cable and standard GPIB cable and found to comply within the limits for a Class A computing device pursuant to Subpart J of Part 15 of FCC Rules which are designed to provide reasonable protection against such interference when operated in a commercial environment Operation of this equipment in a residential area is likely to cause interference in which case the user at his own expense will be required to take whatever measures may be necessary will be required to take whatever measures may be necessary to correct the interference If the equipment does cause interference to radio or television reception which can be determined by turning the equipment on and off one or more of the following suggestions may reduce or eliminate the problem Operate the equipment and the receiver on different branches of your AC electrical system Move the equipment away from the receiver with which it is interfering Reposition the equipment or receiver Reposition the receiver s antenna Unplug any unused I O cables Untermi
42. MO or SRQI STATUS VAL LINE INPUT 1 STATUS Get status info GPIBERR VAL LINE IN PUT 1 GPIBERR SPERR VAL LINE INPUT 1 SPERR COUNT VAL LINE INPUT 1 COUNT IF STATUS AND amp H4000 lt gt 0 THEN GOTO 1000 If TIMO bit is set we timed out before getting SRQI Go to an error routine at line 1000 IF STATUS AND amp H1000 lt gt 0 THEN GOTO 200 If SRQI bit set go to routine to conduct a serial poll 2 PRINT 1 wait 4 Wait indefinitely to become LACS 87 STATUS VAL LINE INPUT 1 STATUSS Get status info GPIBERR VAL LINE INPUT 1 GPIBERR SPERR V AL LINE INPUT 1 SPERR COUNT VAL LINE INPUT 1 COUNT PRINT 1 rd 10 Now that GPIB MAC is addressed to listen read 10 bytes from the GPIB RESPS INPUTS 10 41 Input 10 bytes from serial port buffer LINE INPUT 1 CNT Input number of valid bytes in CNTS SECTION FOUR FUNCTIONS November 1985 National Instruments wrt Write Data wrt Syntax Purpose Remarks YO function wrt Zcount alist CR data lt CR gt You use wrt to send data over the GPIB The argument count is a numeric string preceded by a number sign The string specifies a number between 1 and 65535 and must not contain a comma count specifies the number of data bytes to send The number of data bytes must not include the carriage return that indicates the end of the programming message The argument data is a string
43. National Instruments Model GPIB MAC User Manual Part Number 320064 01 November 1985 Edition National Instruments 12109 Technology Boulevard Austin Texas 78727 512 250 9119 Copyright 1985 by National Instruments All Rights Reserved LIMITED WARRANTY The GPIB MAC is warranted against defects in materials and work manship for a period of one year from date of shipment National Instruments will repair or replace equipment which proves to be defective during the warranty period This warranty includes parts and labor A Returned Material Authorization RMA number must be obtained from the factory before any equipment is returned for warranty During the warranty period the owner may return failed parts to National Instruments for repair National Instruments will pay the shipping costs of returning the part to the owner All items returned to National Instruments for repair must be clearly marked on the outside of the package with a RMA No other warranty is expressed or implied National Instruments shall not be liable for consequential damages Contact National Instruments for more information IMPORTANT NOTE The material in this manual is subject to change without notice National Instruments assumes no responsibility for errors which may appear in this manual National Instruments makes no commit ment to update nor to keep current the information contained in this document Trademarks GPIB MAC is a trademark of National
44. R FUNCTIONS November 1985 National Instruments gts Go from Active Controller to Standby gts Specialized Controller function Syntax gts bool lt CR gt Purpose Youuse gts to change the GPIB MAC from Active Controller to Standby Controller You use gts when the I O and bus management functions do not meet the needs of your device For example you use gts if you wish to allow two external devices to talk to each other directly The GPIB MAC can selectively participate in the hand shake of the data transfer and hold off the handshake when it detects the END message The GPIB MAC can then take control synchronously without possibly corrupting the transfer Remarks Ifthe argument bool is 1 shadow handshaking is enabled If the argument bool is 0 shadow handshaking is not performed If you call gts without an argument the GPIB MAC returns to you the current controller status CSB O if the GPIB MAC is in Standby without shadow handshaking CSB l if the GPIB MAC is in Standby with shadow handshaking CAC if the GPIB MAC is CIC but is not in Standby i e it is the Active Controller and CIDLE if the GPIB MAC is not the CIC i e is an IDLE Controller gts causes the GPIB MAC to go to the Controller Standby state and to unassert the ATN signal if it is initially the Active Controller gts permits GPIB devices to transfer data without the GPIB MAC participating in the transfer 44 SECTION FOUR FUNCTIONS November 1985
45. R FUNCTIONS November 1985 National Instruments rsc Request or Release System Control TSC Syntax Purpose Remarks Initialization function rsc bool CR You use rsc if some other device in your GPIB system should be System Controller If the argument bool is 1 the GPIB MAC configures itself to be the GPIB System Controller If the argument bool is 0 the GPIB MAC configures itself as not System Controller If you call rse without an argument the GPIB MAC returns to you its System Controller status which is 0 if GPIB MAC is not currently System Controller or 1 if the GPIB MAC is System Controller As System Controller the GPIB MAC can send the Inter face Clear IFC and Remote Enable REN messages to GPIB devices If some other Controller asserts Interface Clear the GPIB MAC cannot respond unless it is configured as not System Controller In most applications the GPIB MAC will be System Controller In some applications the GPIB MAC will never be System Controller In either case rse is used only if the Macintosh is not going to be System Controller while the program executes The IEEE 488 standard does not specifically allow schemes in which System Control can be passed from one device to an other however rsc could be used in such a scheme The GPIB MAC configures itself to be System Control ler at power on Refer also to sic and sre 63 SECTION FOUR FUNCTIONS November 1985 Exam
46. TENTS 1 SECTION ONE Introduction l Introduction to the GPIB MAC 1 Introduction to the IEEE 488 GPIB 1 Description of the Model GPIB MAC 2 Environmental Specifications 2 Physical Specifications 3 Quick Reference Chart 3 The Model GPIB MAC Front Panel 4 The Model GPIB MAC Back Panel 6 Mechanical Specifications 6 Electrical Specifications 7 SECTION TWO Installation and Configuration 7 Inspection 7 Installation 7 Voltage Requirements 8 Configure the GPIB MAC Rear Panel Switches 8 Switches 1 and 2 Factory Use Only 9 Switch 3 Word Length 10 Switch 4 Stop Bits 11 Switches 5 and 6 Parity Type 12 Switches 7 8 and 9 Baud Rate 14 Connect Cables 15 Turn Power Switch to On 17 SECTION THREE Programming the GPIB MAC 17 Programming Messages 17 Programming Message Format 18 How Messages are Processed 18 Function Names 19 Function Argument Delimiters 19 Abbreviations for Arguments 19 GPIB Address 20 Numeric String Argument 20 Status Information 21 Serial Port Error Handling 21 GPIB Read and Write Termination Method 22 Default Settings ix TABLE OF CONTENTS November 1985 National Instruments 22 23 25 25 25 27 27 29 31 33 35 38 39 42 44 46 47 48 50 52 54 56 58 61 63 65 List of Functions by Group GPIB Functions Serial Port Functions General Use Functions List of Functions in Alphabetical Order SECTION FOUR Functions Points to Remember cac Become Active C
47. Thus the configuration byte for each of them is 01101000 hex 68 When a parallel poll is conducted the controller can immediately find out if all line printers are free because the response in this situation will be 0 If any line printer is busy bit O of the parallel poll response will be 1 corres ponding to DIO line 1 being asserted But what if the active con troller wants to know if one line printer is free If the controller reconfigures the line printers to respond positively when free dio ss 0 0 0 configuration byte 01 1000000 then if any device is free it will drive the DIO line to 1 Thus the controller can use S bit ist bit correspondence for different types of information 120 APPENDIX F PARALLEL POLLING November 1985 National Instruments Appendix G Setting Switches This appendix explains how to set the switches on the back panel of the GPIB MAC You may change the serial port characteristics of the Macintosh from within BASIC or other programming languages The default characteristics of the Macintosh modem port are as follows baud rate 9600 parity none data bits 8 stop bits 2 If these defaults meet your needs set the switches on the GPIB MAC as follows You may want to change the default characteristics of the serial port on the Macintosh For instance you may want to run at a higher baud rate up to 57 6K baud To change the default characteristics to 57 6K baud no parity 8 data
48. alist CR You use clr to reset the internal or device functions of the specified devices For example a multimeter might require that you send it either the GPIB Device Clear or Selected Device Clear command to change its function range and trigger mode back to its default setting Use clr to do this The argument alist is a list of addrs separated by commas or spaces addrs are device addresses that specify the GPIB addresses you wish to clear alist may consist of only one addr A device address consists of a primary address and an optional secondary address The secondary address is separated from the primary address by a plus sign Only the lower five bits of each address are significant These bits may be in the range from 0 through 30 for both the primary and the secondary address Therefore the binary value 01100010 decimal 98 is interpreted as decimal 2 The following examples all specify a primary address of 0 and a secondary address of 2 The listen address is 32 the talk address is 64 and the secondary address is or 98 which are equivalent 0 2 or 04 98 or 324 98 or 0 x62 If you call elr with alist the GPIB MAC clears only the devices specified in alist Selected Device Clear If you call clr without alist the GPIB MAC clears all devices Device Clear 33 SECTION FOUR FUNCTIONS November 1985 National Instruments If this is the first function you call that requires GPIB controller capab
49. all subsequent data bytes You may use the spign function to tell the GPIB MAC to ignore all serial port errors in which case the data bytes are sent even if they contain serial port errors NSER 0 The GPIB MAC reports this error when the GPIB MAC detected no serial port error as a result of the last operation EPAR 1 103 The GPIB MAC records this error when the parity of the received character is not what was expected This means APPENDIX B STATUS INFORMATION November 1985 National Instruments that 1 or more bits of the received character were corrupted in such a way as to change the character s parity EORN 2 The GPIB MAC records this error when characters arrive at the serial port faster than the serial port can accept them When this error occurs one or more characters sent to the serial port have been lost If this error occurs check to see that the GPIB MAC and your Macintosh are using the same serial port settings EOFL 3 The GPIB MAC records this error when the GPIB MAC s internal serial port buffer overflows This should only occur if XON XOFF is disabled EFRM 4 The GPIB MAC records this error when a character is received whose stop bits are not in the expected place This can happen when the number of bits per character setting of the GPIB MAC does not match your Macintosh It can also happen if the baud rates of the GPIB MAC and your Macintosh do not match or if one side of the serial link does not
50. and its own talk address Interface Clear IFC or gts is called without shadow handshake 99 APPENDIX B STATUS INFORMATION November 1985 National Instruments DTAS 2 The DTAS bit specifies whether the GPIB MAC has detected a device trigger command The DTAS bit is set whenever the GPIB MAC as a Listener detects the Group Execute Trigger GET command has been sent by another Controller The DTAS bit is cleared in status at the start of any subsequent programming message DCAS I The DCAS bit specifies whether the GPIB MAC has detected a device clear command The DCAS bit is set whenever the GPIB MAC detects the Device Clear DCL command has been sent by itself or by another Controller or whenever the GPIB MAC as a Listener detects the Selected Device Clear SDC command has been sent by itself or by another Controller The DCAS bit is cleared in Status at the start of any subsequent programming message In addition to the above the following situations also affect the bits in status A call to the onl function clears the following bits END LOK REM CIC TACS LACS DTAS DCAS A call to onl affects bits other than those listed here according to the rules explained for each bit GPIB Error Codes When the ERR bit is set in Status a GPIB or a serial port error has occurred The error code is indicated by gpib error or serial error The following paragraphs describe the gpib errors in detail 100 APPENDIX B STATUS INFORM
51. and send all data even if serial port errors occur 72 SECTION FOUR FUNCTIONS November 1985 National Instruments sre Set or Clear Remote Enable sre Syntax Purpose Remarks Specialized Controller function sre bool CR You use sre if the I O and bus management functions do not meet the needs of your device Sre gives you more precise control over the GPIB Use sre to turn the Remote Enable signal on and off sre is not a function you will use frequently because in most cases the first I O or bus management function you call will set remote enable automatically If the argument bool is 1 the GPIB MAC asserts the Remote Enable REN signal If the argument bool is 0 the GPIB MAC unasserts REN Many GPIB devices have a remote program mode and a local program mode It is usually necessary to place devices in remote mode before programming them from the GPIB A device enters the remote mode when the REN line is asserted and the device receives its listen address Use cmd to send a device its listen address after using sre Use loc to return the device to local program mode If you call sre with an argument and the GPIB MAC is not System Controller the GPIB MAC records the ESAC error If you call sre without an argument the GPIB MAC returns its current remote status 1 remote O local Refer also to rsc cmd and loc 73 SECTION FOUR FUNCTIONS November 1985 National Instruments Exam
52. andard TTL logic levels When DAV is true for example it is a TTL low level lt 0 8V and when DAV is false it is a TTL high level gt 2 0V Configuration Restrictions To achieve the high data transfer rate that the GPIB is designed for the physical distance between devices and the number of devices on the bus is limited The following restrictions are typical A maximum separation of four meters between any two devices and an average separation of two meters over the entire bus A maximum total cable length of 20 meters No more than 15 devices connected to each bus with at least two thirds powered on Bus extenders are available from National Instruments and other manufacturers for use when these limits must be exceeded 114 APPENDIX D OPERATION OF THE GPIB November 1985 National Instruments Appendix E Common Questions This appendix gives answers to common questions Question Why does the manual suggest that I use INPUT sometimes and LINE INPUT at other times Microsoft suggests using INPUT to read from the serial port Answer Use LINE INPUT to read status information from the GPIB MAC GPIB MAC software formats its status information so that your BASIC program may easily read and interpret each of its pieces Each logical piece of status information is followed by a carriage return and linefeed LINE INPUT allows you to easily read each piece of status information and assign it to a v
53. ariable Use INPUTS to read a data string from your GPIB device INPUTS requires that you know the exact number of characters you wish to read from the serial port When reading status information from the GPIB MAC this is not always possible since the responses may vary in length from one call to the next But when reading a data string from your GPIB device you requested a certain number of bytes and you should use INPUTS to read the number of bytes you requested in your rd function The GPIB MAC appends to the end of the data string a string containing the number of bytes that were actually read from the GPIB So once you read in the data bytes using INPUTS use LINE INPUT to read the string containing the byte count Refer to the example following the rd function description in Section Four 115 APPENDIX E COMMON QUESTIONS November 1985 National Instruments Question When I use LINE INPUT my strings are usually preceded by a linefeed and followed by a carriage return Why don t my strings contain both a carriage return and linefeed at the end Answer LINE INPUT stops reading when a carriage return is seen and does not skip over the linefeed in the sequence The linefeed is not read until the following LINE INPUT In most cases you will be using the VAL function to convert the string to a value and a leading linefeed is ignored Question I sent the programming message rsp 10 to the GPIB MAC to serial poll device
54. duct a parallel poll of previously configured devices by sending the IDY message ATN and EOI both asserted and reading the response from the GPIB data lines The GPIB MAC pulses the IDY message for greater than or equal to 2 microseconds and expects valid responses within that time It remains Active Controller afterward The GPIB MAC returns the Parallel Poll Response PPR following the poll in the form of a numeric string representing the decimal value of the response If this is the first function you call that requires GPIB controller capability and you have not disabled System Controller capability with rse the GPIB MAC sends Interface Clear IFC to make itself CIC It also asserts Remote Enable If you passed control to some other GPIB device control must be passed back to you or you must send IFC to make yourself CIC before making this call Otherwise the ECIC error will be posted Refer also to ist PPC ppu and to Appendix F on parallel polls 61 SECTION FOUR FUNCTIONS November 1985 National Instruments Example PRINT 1 ppc 13 1 015 3 0 CHR 13 rpp Configure 2 devices for parallel polls and poll them response 5 lt CR gt lt LF gt both devices responded positively LINE INPUT 1 RESP PPR VAL RESP Get parallel poll response from serial port buffer and assign it to integer variable PPR PRINT 1 ppu Unconfigure all devices from parallel polls 62 SECTION FOU
55. e address as a parameter ppu sends the device the Parallel Poll Disable command hex 70 binary 01 1 1 0000 which sets U to 1 to disable the device from responding to a parallel poll To unconfigure all devices the controller may call ppu with no arguments which sends PPU parallel poll unconfigure hex 15 Example A system has three line printers two tape drives one card reader and one PC on a system The PC uses a GPIB MAC to communicate on the GPIB All other devices are GPIB devices The PC is designated to be active controller and all other devices recognize this Furthermore all devices will set their ist bit to 1 when they are busy and 0 when they are free 119 APPENDIX F PARALLEL POLLING November 1985 National Instruments The active controller configures the card reader at address 6 to respond positively on DIO line 4 which sets bit 3 of the response byte when free by sending the configuration byte 01100011 The S bit is set to 0 the value of bits O 2 is 3 PPC 6 4 0 When a parallel poll is conducted one of two things will happen If the card reader is free bit 3 of the response byte will be 1 if it is busy bit 3 will be 0 When the device is free its ist bit is 0 and because this equals the value of the S bit the device asserts DIO line 4 The active controller configures the line printers to all respond positively on DIO line 1 when busy In this case the ppr s argument for each of them is 0 1
56. ecifies the number of bytes to read count must not contain a comma It can specify a number between 1 and 65535 The argument addr is a device address that specifies the address of the device to be addressed as a Talker addr consists of a primary address and an optional secondary address The secondary address is separated from the primary address by a plus sign Only the lower five bits of each address are significant These bits may be in the range from 0 through 30 for both the primary and the secondary address Therefore the binary value 01100010 decimal 98 is interpreted as decimal 2 The following examples all specify a primary address of 0 and a secondary address of 2 The listen address is 32 the talk address is 64 and the secondary address is 2 or 98 which are equivalent 042 or 0498 or 32498 or 0 Ax62 The GPIB MAC reads data from the GPIB until the specified byte count is reached the GPIB END message is received with a data byte the EOS byte is received or a timeout occurs Refer also to eos eot and tmo 58 SECTION FOUR FUNCTIONS November 1985 National Instruments Because you may not know for certain the number of bytes actually read from the GPIB the GPIB MAC returns the received GPIB data to you as follows First the GPIB MAC returns to you all bytes it read from the GPIB Next it sends null bytes until the total number of bytes returned to you matches your requested count Finally it retur
57. ect and control programmable instruments manufactured by them Because of its high system data rate ceilings of from 250K bytes to 1M byte per second the GPIB quickly became popular in other applications such as intercomputer communication and peripheral control It was later accepted as the industry standard IEEE 488 The versatility of the system prompted the name General Purpose Interface Bus Types of Messages Devices on the GPIB communicate by passing messages through the interface system There are two types of messages Device dependent messages often called data or data messages contain device specific information such as programming instructions measurement results machine status and data files Interface messages manage the bus itself They are usually called commands or command messages Interface messages perform such functions as initializing the bus addressing and unaddressing devices and setting devices for remote or local programming The term command as used here should not be confused with some device instructions which are also call commands Such device specific instructions are actually data messages Talkers Listeners and Controllers There are three types of GPIB communicators A Talker sends data messages to one or more Listeners The Controller manages the flow of information on the GPIB by sending commands to all devices 107 APPENDIX D OPERATION OF THE GPIB November 1985 National Instrum
58. en address is 32 the talk address is 64 and the secondary address is 2 or 98 which are equivalent 0 2 or 0498 or 32498 or 04 x62 If you call ppu with alist the GPIB MAC unconfigures from parallel polls only those devices specified in alist If you call ppU without alist the GPIB MAC unconfigures all devices from parallel polls 56 SECTION FOUR FUNCTIONS November 1985 National Instruments If this is the first function you call that requires GPIB controller capability and you have not disabled System Controller capability with rse the GPIB MAC sends Interface Clear IFC to make itself CIC It also asserts Remote Enable If you passed control to some other GPIB device control must be passed back to you or you must send IFC to make yourself CIC before making this call Otherwise the ECIC error will be posted If the address of the GPIB MAC is included in alist the GPIB MAC disables itself from responding to parallel polls Refer also to ist ppc rpp and to Appendix F on parallel polls Examples 1 PRINT 1 ppu 14 Send the PPU command to device 14 2 PRINT 1 PPU Send the PPU command to all devices 57 SECTION FOUR FUNCTIONS November 1985 National Instruments rd Read Data rd Syntax Purpose Remarks I O function rd count addr CR You use rd to read data from the GPIB The argument count is a numeric string preceded by a number sign f count sp
59. ent 0 InitWindows TEInit Initialize TextEdit InitDialogs NULL InitCursor Clear the Screen EraseRect amp thePort portRect TextFont 4 Monaco TextFace 0 plain TextSize 9 open serial drivers if rc OpenDriver P AOut amp refAOut myExit Can t open modem port re d n rc if rc OpenDriver P AIn amp refAIn myExit Can t open modem port rc d n rc set baud stop databits setupport refAIn refAOut make buffer too big for input to overrun 9 for inLen 1 14 inLen 32 amp amp pBufIn NULL inLen gt gt 1 must be room here somewhere 6 pBufIn NewPtr long inLen if SerSetBuf refAIn pBufIn inLen tbox SerSetBuf error load file and send fload refAIn refAOut main setupport refIn refOut short refIn refOut short parity stopbits databits baud char c SerShk flgs serial port handshake flags int rc result code EventRecord theEvent set serial port attributes flgs fXOn TRUE output flow control flgs fCTS FALSE not hardware flow control flgs xOn 021 Qe 128 APPENDIX I SERIAL PORT SAMPLE PROGRAM November 1985 National Instruments flgs xOff 023 S f flgs errs hwOverrunErr framingErr flgs evts 0 flgs fInX FALSE not input flow control if rc SerHShake refOut amp flgs myExit S
60. ents Devices can be Talkers Listeners and or Controllers A digital multimeter for example is a Talker and may also be a Listener A printer or plotter is usually only a Listener A computer on the GPIB will often combine all three roles to manage the bus and communicate with other devices The GPIB is a bus like a typical computer bus except that the computer has its circuit cards interconnected via a backplane bus whereas the GPIB has standalone devices interconnected via a cable bus The role of the GPIB Controller can also be compared to the role of the computer s CPU but a better analogy is to the switching center of a city telephone system The switching center Controller monitors the communications network GPIB When the center Controller notices that a party device wants to make a call send a data message it connects the caller Talker to the receiver Listener The Controller usually addresses a Talker and a Listener before the Talker can send its message to the Listener After the message is transmitted the Controller usually unaddresses both devices Some bus configurations do not require a Controller For example one device may only be a Talker called a Talk only device and there may be one or more Listen only devices A Controller is necessary when the active or addressed Talker or Listener must be changed The Controller function is usually handled by a computer System Controller and Active Controll
61. er Although there can be multiple Controllers on the GPIB only one Controller at a time is Active Controller or Controller in Charge CIC Active control can be passed from the current Active Controller to an idle Controller Only one device on the bus the System Controller can make itself the Active Controller 108 APPENDIX D OPERATION OF THE GPIB November 1985 National Instruments GPIB Signals The interface bus consists of 16 signal lines and 8 ground return or shield drain lines The 16 signal lines are divided into three groups 8 datalines 3 handshake lines 5 interface management lines The following figure shows the arrangement of these signals on the GPIB cable connector D102 DI06 D103 DI07 DIO4 DIOS EOI REN DAV GND PAIR W DAV NRFD GND TW PAIR W NRFD NDAC GND PAIR W NDAC IFC TW PAIR W IFC SRQ GND TW PAIR W SRQ ATN GND TW PAIR W ATN SHIELD SIGNAL GROUND GPIB Cable Connector 109 APPENDIX D OPERATION OF THE GPIB November 1985 National Instruments Data Lines The eight data lines DIO1 through D108 carry both data and command messages All commands and most data use the 7 bit ASCII or ISO code set in which case the 8th bit D108 is unused or used for parity Appendix A lists the GPIB command messages Handshake Lines Three lines asynchronously control the transfer of message bytes among devices The process is called a three wire interlocked handshake and it guarantees that m
62. erHShake error rc d n rc baud baud57600 puts Current baud 57600 enter s for 19200 while GetNextEvent keyDownMask amp theEvent wait for key down if char theEvent message s baud baud19200 parity noParity stopbits stop20 databits data8 SerReset refIn short baud parity stopbits databits SerReset refOut short baud parity stopbits databits myExit str rc char str int rc printf str rc exit 0 fload refIn refOut load and send a file short refIn refOut char s SFReply reply StringHandle hStr short refNum int rc result code register long pause long logEOF length of file static SFTypeList typelist TEXT static Point where 100 70 SFGetFile pass where OL 1 typeList OL amp reply while reply good EraseRect amp thePort gt portRect if SetVol NULL reply vRefNum 129 APPENDIX I SERIAL PORT SAMPLE PROGRAM November 1985 National Instruments send tbox Can not SetVol continue if FSOpen reply fName reply vRefNum amp refNum tbox Can t open file continue get end of file if rc GetEOF refNum amp logEOF tbox Can t find EOF continue printf EOF ld n logEOF get buffer for file S NewPtr logEOF if s NULL tbox File size too large for memory continue read file into buffer if
63. es Hex Octal Decimal ASCI Message Hex Octal Decimal ASCII Message 00 000 O0 NUL 20 040 382 SP MLA 01 001 1 SOH GTL 21 041 33 MLA 02 002 2 STX 22 042 34 MLA 03 003 3 ETX 23 043 35 MLA 04004 4 EOT SDC 24 044 36 MLA 05 005 5 ENQ PPC 25 045 37 MLA 06 006 6 ACK 26 046 38 amp MLA 07 007 7 BEL 27 047 39 MLA 08 6010 8 BS GET 28 050 40 MLA 09 011 9 HT TCT 29 051 141 MLA OA 012 10 LF 2A 052 42 MLA OB 018 11 VT 2B 053 43 MLA OC 014 12 FF 2c 054 444 MLA OD 015 13 CR 2D 055 45 MLA OR 016 14 SO 2E 056 46 MLA OF 017 15 I 2F 057 47 MLA 10 020 16 DLE 30 060 48 0 MLA 11 021 17 DCI LLO 31 061 49 1 MLA 12 022 18 DC2 32 062 50 2 MLA 13 023 19 DC3 33 063 5l 3 MLA 14 024 20 DC4 DCL 34 064 52 4 MLA 15 025 21 NAK PPU 35 065 53 5 MLA 16 026 22 SYN 36 066 54 6 MLA 17 027 23 ETB 37 067 55 7 MLA 18 030 24 CAN SPE 38 070 56 8 MLA 19 031 25 EM SPD 39 O71 57 9 MLA 1A 032 26 SUB 3A 072 58 MLA IB 033 27 ESC 3B 073 59 MLA 1C 034 28 FS 3c 074 60 lt MLA ID 035 29 GS 3D 075 61 MLA 1E 036 30 RS 3E 076 62 gt MLA 1F 037 381 US 3F 07 63 UNL 94 APPENDIX A MULTILINE INTERFACE MESSAGES November 1985 National Instruments Multiline Interface Messages Hex Octal Decimal ASCII Message Hex Octal Decimal ASCII Message 40 100 64 MTA 60 140 96 lt MS A PPE 41 100 65 A MTA 61 141 97 a MS A PPE 42 102 66 B MTA 62 142 98 b MS A PPE 43 103 67 C MTA 63 143 099 c MS A PPE 44 104 68 D MTA 64 144 100 d MS A PPE 45 105 69
64. es The instructions for each GPIB device explain when you should trigger them and what effect the trigger has The argument alist is a list of addrs separated by commas or spaces addrs are device addresses that specify the GPIB addresses you wish to trigger A device address consists of a primary address and an optional secondary address The secondary address is separated from the primary address by a plus sign Only the lower five bits of each address are significant These bits may be in the range from 0 through 30 for both the primary and the secondary address Therefore the binary value 01100010 decimal 98 is interpreted as decimal 2 The following examples all specify a primary address of 0 and a secondary address of 2 The listen address is 32 the talk address is 64 and the secondary address is 2 or 98 which are equivalent 0 2 or 0498 or 324 98 or O x62 If you call trg without an argument the EARG error is posted If this is the first function you call that requires GPIB controller capability and you have not disabled System Controller capabiltity with rsc the GPIB MAC sends Interface Clear IFC to make itself CIC It also asserts Remote Enable 83 SECTION FOUR FUNCTIONS November 1985 National Instruments If you passed control to some other GPIB device control must be passed back to you or you must send IFC to make yourself CIC before making this call Otherwise the ECIC error will be posted
65. essage bytes on the data lines are sent and received without transmission error NRFD not ready for data NRFD indicates when a device is ready or not ready to receive a message byte The line is driven by all devices when receiving commands and by Listeners when receiving data messages NDAC not data accepted NDAC indicates when a device has or has not accepted a message byte The line is driven by all devices when receiving commands and by Listeners when receiving data messages DAV data valid DAV tells when the signals on the data lines are stable valid and can be accepted safely by devices The Controller drives DAV when sending commands and the Talker drives it when sending data messages The way in which NRFD and NDAC are used by the receiving device is called the Acceptor Handshake Likewise the sending device uses DAV in the Source Handshake 110 APPENDIX D OPERATION OF THE GPIB November 1985 National Instruments Interface Management Lines Five lines are used to manage the flow of information across the interface ATN attention The Controller drives ATN true when it uses the data lines to send commands and false when it allows a Talker to send data messages IFC interface clear The System Controller drives the IFC line to initialize the bus to become Controller In Charge REN remote enable The System Controller drives the REN line which is used to place devices in remote or local pro
66. et in the returned status indicators To prevent the GPIB MAC from waiting indefinitely for SRQ to be asserted set the SRQI and TIMO bits by setting the mask equal to 4096 16384 This will cause the wait to terminate either on SRQI or TIMO whichever occurs first 85 SECTION FOUR FUNCTIONS November 1985 National Instruments It is recommended that you always include the TIMO bit value in mask when you wait for an event WAIT MASK VALUES Hex Decimal Mne Bit Value Value monic Description 15 Reserved 14 4000 16384 TIMO Timeout 13 Reserved 12 1000 4096 SRQI SRQ detected while CIC 11 Reserved 10 Reserved 9 Reserved 8 Reserved 7 80 128 LOK Lockout state 6 40 64 REM Remote state 5 20 32 CIC Controller In Charge 4 10 16 ATN Attention asserted 3 8 8 TACS Talker active 2 4 4 LACS Listener active 1 2 2 DTAS Device trigger state 0 1 1 DCAS Device clear state If mask 0 the function completes immediately If the TIMO bit is 0 or the timeio time limit is set to 0 with tmo timeouts for this function are disabled You should disable timeouts only when you are certain the selected event will occur otherwise the GPIB MAC waits indefinitely for the event to occur If you call wait without an argument the GPIB MAC records the EARG error Refer also to stat and tmo 86 SECTION FOUR FUNCTIONS November 1985 National Instruments Examples l PRINT 1 wait x5000 Wait for TI
67. ex 7X parallel poll is disabled S when the device s ist individual status bit matches the S bit the device will assert the appropriate data line true hex 60 hex 67 set S to 0 hex 68 hex 6F set S to 1 DIO The value n in bits O 2 corresponds to one of the DIO lines 1 8 where n corresponds to DIO line n l Thus a value of 2 binary 010 corresponds to DIO line 3 117 APPENDIX F PARALLEL POLLING November 1985 National Instruments The circumstances under which a device sets its ist bit are specific to that device For example a device might always set the ist bit to 1 when it is busy and 0 when it is free or vice versa Consult your device documentation for this information With this information the controller can configure devices according to the information desired Only the active controller can perform a parallel poll There are two steps to conducting a parallel poll the configuration step and the actual polling The following paragraphs describe these two steps Configuration The ppc function configures devices for parallel polls For example if you want to configure a device at address 5 to respond on DIO line 3 when the ist bit is 1 the programming message would be ppc 5 3 1 The GPIB MAC takes the arguments 3 1 and constructs the following parallel poll enable byte U S DIOlines 1 8 0 11 IO 1 1 0 1 0 The value of this byte is hex 6A where U 0 enable S 1 thus when ist
68. f the new GPIB MAC serial poll response byte The serial poll response byte is the status byte the GPIB MAC provides when serially polled by another device that is CIC If bit 6 hex 40 RQS bit is also set the GPIB MAC additionally requests service by asserting the SRQ line If you call rsv without an argument the GPIB MAC returns a numeric string containing the decimal value of its serial poll status byte Examples 1 PRINT 1 rsv x46 Request service with serial poll response 6 2 PRINT 1 rsv What is the current serial poll status byte response 70 lt CR gt lt LF gt The current status byte decimal 70 or hex 46 68 SECTION FOUR FUNCTIONS November 1985 National Instruments sic Send Interface Clear Sic Specialized Controller function Syntax sic time CR Purpose Remarks You use sic if the initialization I O and bus manage ment functions do not meet the needs of your device and you wish more precise control over the GPIB sic makes the GPIB MAC CIC and initializes the GPIB sic is not a function you will use frequently because in most cases the first I O or bus management function you call will do this automatically The argument time is a numeric string specifying any number of seconds between 0001 and 3600 which corresponds to time limits between 100 microseconds and 1 hour time must not contain a comma If you call sic without an argument IFC is sent for 50
69. gram mode SRQ service request Any device can drive the SRQ line to asynchronously request service from the Active Controller with the SRQ line EOI end or identify The EOI line has two purposes The Talker uses it to mark the end of a message string The Active Controller uses it to tell devices to identify their responses in a parallel poll Physical and Electrical Characteristics Devices are usually connected with a cable assembly consisting of a shielded 24 conductor cable with both a plug and receptacle at each end This design allows devices to be connected in either a linear or a star configuration or a combination of the two See the following figures 111 APPENDIX D OPERATION OF THE GPIB November 1985 National Instruments Macintosh with GPIB MAC Device B Device C Linear Configuration of GPIB Devices 112 APPENDIX D OPERATION OF THE GPIB November 1985 National Instruments Macintosh with GPIB MAC CLELTTTITITLILELTIT LLLTIIITTITIIIIT WLIILIIIIITIIILLLD UB COSTAE P S Device A Device D Device B Device C Star Configuration of GPIB Devices 113 APPENDIX D OPERATION OF THE GPIB November 1985 National Instruments The standard connector is the Amphenol or Cinch Series 57 MICRORIBBON or AMP CHAMP type An adapter cable using non standard cable and or connector is used for special interconnect applications The GPIB uses negative logic with st
70. he status information corresponds to the current programming message For example suppose you call stat c S to set up continuous status reporting After reading the status information returned for the stat call you call wrt The GPIB MAC then returns the status information that corresponds to the wrt message Refer to the following examples for ways in which to make use of the status information When you wish to begin continuous status reporting send the stat c s stat c n or stat c n S programming message Status information will be immediately returned indicating the current status conditions When 78 SECTION FOUR FUNCTIONS November 1985 National Instruments you call stat with both s and n the numeric status is always returned first If you call stat without an argument continuous status reporting is disabled Notice that when you send several programming messages to the GPIB MAC it buffers them and processes each one without any delay in between However if you enable continuous status reporting and check the status of each programming message before sending the next the GPIB MAC waits for each subsequent programming message to arrive at the serial port before processing it This slows down the overall performance of your program If speed is a primary concern disable continuous status reporting Examples l 79 10 20 30 40 50 60 70 80 90 100 110 120 400 410 420 500 510 520 530 540
71. ign Both addresses are expressed as numeric strings Only the lower five bits of each address are significant These bits may be in the range from 0 through 30 for both the primary and the secondary address Therefore the binary value 01100010 decimal 98 is interpreted as decimal 2 The following examples all specify a primary address of 0 and a secondary address of 2 The listen address is 32 the talk address is 64 and the secondary address is 2 or 98 which are equivalent 0 2 or 0498 or 324 98 or 0 x62 If you specify a primary address without a secondary address secondary addressing is disabled If you call caddr without an argument the GPIB MAC returns to you its current GPIB address The address assigned by this function remains in effect until you call caddr again call onl or you turn off the GPIB MAC 31 SECTION FOUR FUNCTIONS November 1985 National Instruments The power on default is 0 with secondary addressing disabled Examples 1 PRINT 1 caddr 0422 Give GPIB MAC a primary address of 0 and a secondary address of 22 2 PRINT 41 CADDR 1 Change GPIB MAC primary address to 1 and disable secondary addressing 3 PRINT 1 CADDR Return current GPIB MAC address response 1 lt CR gt lt LF gt 32 SECTION FOUR FUNCTIONS November 1985 National Instruments clr Clear Specified Device clr Syntax Purpose Remarks Bus Management function clr
72. ility and you have not disabled System Controller capability with csc the GPIB MAC sends Interface Clear IFC to make itself CIC It also asserts Remote Enable Refer to Appendix D for more information on clearing devices Refer to Appendix B for more error information Examples 1 PRINT 1 clr 144 30 16 12 18 3 26 6 Selectively clear 5 devices 2 PRINT 1 CLR Issue Device Clear to all devices frequently used function 34 SECTION FOUR FUNCTIONS November 1985 National Instruments cmd Send GPIB Commands cmd Specialized Controller function Syntax cmd fcount CR Purpose Remarks commands CR You use cmd when the L O and bus management functions do not meet the needs of your device cmd allows you precise control over the GPIB For example in applications that require command sequences not sent by other functions cmd allows you to transmit any sequence of interface messages commands over the GPIB The argument count is a numeric string preceded by a number sign count specifies the number of GPIB command bytes interface messages to send which is a number between 1 and 255 The number of command bytes must not include the carriage return or linefeed that you include to indicate the end of the programming message The argument commands is a list of GPIB commands These commands are represented by their ASCII character equivalents For example the GPIB Untalk UNT
73. it If 230 VAC is required use a cable that is compatible with both the GPIB MAC power receptacle and the 230 VAC plug configuration The GPIB cable should be connected to the 24 pin GPIB connector on the lower right of the rear panel The connectors can be piggy backed to add more GPIB devices to the bus Connect the serial cable to the 9 pin D subminiature connector on the back of the GPIB MAC Connect the other end of the cable to your Macintosh modem port 14 SECTION TWO INSTALLATION AND CONFIGURATION November 1985 National Instruments Turn Power Switch to On The power switch is located at the left of the power cord receptacle Turn the switch to On There will be a slight delay while the unit performs a self test of all the internal circuitry The test does not affect devices connected to the GPIB MAC When the test successfully completes the BEADY LED comes on If it does not verify your switch settings and the power connections If the BEADY LED still fails to come on contact National Instruments Note The rear panel switches are read by the fiiware only when the unit is powered on After changing switch settings turn the power switch off and back on for the change to take effect Also the GPIB address of the GPIB MAC at power on is 0 with secondary addressing disabled You can change these values after power on using a programming message 15 SECTION TWO INSTALLATION AND CONFIGURATION November 1985 National
74. itv Type The GPIB MAC can transmit and receive serial data using odd parity even parity or no parity Configure the GPIB MAC for the correct parity according to the following figure Note that switch 5 indicates parity off Switch 6 indicates parity odd or even If switch 5 is set to off switch 6 is ignored Switch Settin Parity Type 415 6 ND v Even Parity Perity Inhibit Parity Inhibit 11 SECTION TWO INSTALLATION AND CONFIGURATION November 1985 National Instruments 1 8 and 9 B R Configure the GPIB MAC for the appropriate baud rate by setting switches 7 8 and 9 according to the following figures Switch Settings Baud Rate 300 2400 4800 12 SECTION TWO INSTALLATION AND CONFIGURATION November 1985 National Instruments witch in Baud 9600 19 2K 38 4K 57 6K If you need more information on how the switches of the GPIB MAC should be set refer to Appendix G 13 SECTION TWO INSTALLATION AND CONFIGURATION November 1985 National Instruments Connect Cables You must connect three cables to operate the GPIB MAC the serial cable the power cable and the GPIB cable The three cables all connect to the GPIB MAC via the rear panel as shown in the following figure oo alae with Serial Cable Power Cable and GPIB able The power cord receptacle is located at the top left of the rear panel If 115 VAC is required use the standard power cable supplied with the un
75. ler s end 101 APPENDIX B STATUS INFORMATION November 1985 National Instruments EADR 3 The GPIB MAC records this error when it is not addressed to listen or to talk before read and write calls when it is not the Controller In Charge The remedy is to be sure that the Controller addresses the GPIB MAC to talk or listen before attempting the wrt or rd EARG 4 The GPIB MAC records this error when you pass an invalid argument to a function call The following are some examples tmo called with a value not in the range OOOOI 3600 sic called with a value not in the range OOOI 3600 eos called with meaningless termination method identifiers caddr called with the value 31 63 95 or 127 ppc called with illegal parallel poll configurations If your programming message contains more than one argument and you get this error the GPIB MAC discards all arguments and does not perform the function This also may be caused by a transmission error which corrupts the argument portion of the programming message or which corrupts the CR or lt LF gt that terminates the programming message Use stat and check serial error to determine if a transmission error has occurred ESAC 5 The GPIB MAC records this error when Sic or sre is called when the GPIB MAC does not have System Controller capability The remedy is to give the GPIB MAC that capability by calling rsc At power on the GPIB MAC assumes itself to be the System Controller E
76. ls Go to Local Place the GPIB MAC online offline Pass Control Parallel Poll Configure Parallel Poll Unconfigure Read data Request conduct a Parallel Poll Request or release System Control Request conduct a serial poll Request service set or change the serial poll status byte Send interface clear Ignore serial port errors Set or clear remote enable Return GPIB MAC status Change or disable time limit Trigger selected device s Wait for selected event write data Change serial port XON XOFF protocol 26 SECTION THREE PROGRAMMING THE GPIB MAC November 1985 National Instruments Section Four Functions This section contains descriptions of functions which you use to program the GPIB MAC These functions are in alphabetical order and are formatted to provide you a handy reference Points to Remember l 2T The programming examples for each function description are in Microsoft BASIC version 2 0 In the syntax portion of the function descriptions arguments enclosed in brackets are optional Do not enter the brackets as part of your argument Terminate each programming message with a carriage return lt CR gt a linefeed lt LF gt or a carriage return followed by a linefeed lt CR gt lt LF gt The terminator is denoted by CR in the syntax portions of the function descriptions In the program ming examples the BASIC PRINT statement automatically sends a carriage return at the end of
77. ments The following examples all specify a primary address of 0 and a secondary address of 2 A plus sign 4 separates the primary address from the secondary address The listen address is 32 primary address plus 32 the talk address is 64 primary address plus 64 and the secondary address is 2 or 98 which are equivalent The next paragraph explains the x notation 0 2 or 0 98 or 32498 or 0 x62 Numeric String Argument Another type of argument is a numeric string A numeric string represents an integer which you may express using decimal octal or hexadecimal digits To specify an octal integer precede it with a backslash To specify a hexadecimal integer precede it with a backslash x x or backslash X X Each of the following numeric strings represents the decimal integer value 112 112 160 x70 The GPIB address argument described previously under GPIB Address consisted of one or two numeric strings Status Information The function descriptions in Section Four explain that the GPIB MAC records specific status and error information This means that it stores that information in its memory so that the status information is available to you when you request it The function descriptions also explain that the GPIB MAC returns to you certain information This means that the GPIB MAC sends information to you over the serial port You then read this information from your serial port 20 SECTION THREE
78. nated I O cables are a potential source of interference Remove any unused circuit boards Unterminated circuit boards are also a potential source of interference Be sure the computing device is plugged into a grounded outlet and that the grounding has not been defeated with a cheater plug Replace the GPIB cable with Hewlett Packard Model 10833 cable If none of these measures resolves your interference problems contact the manufacturer or write to the U S Government Printing Office Washington D C 20402 for the booklet How to Identify and Resolve Radio TV Interference Problems Stock Number 004 000 000345 4 November 1985 National Instruments Preface Welcome to the family of National Instruments GPIB products and to the Model GPIB MAC The Model GPIB MAC allows the GPIB to be controlled from a Macintosh personal computer About the Manual The manual is designed for users who have some familiarity with the Macintosh personal computer the GPIB and test and meas urement equipment For users with less experience we have included appendixes that describe the operation of the GPIB For more specific details on the operation of the GPIB refer to the IEEE Std 488 1978 IEEE Standard Digital Interface for Program mable Instrumentation Whatever your level of experience if you encounter problems National Instruments has a staff of applications engineers ready to help you with your particular p
79. ns a numeric string representing the number of bytes that it actually read from the GPIB For example if you send the GPIB MAC the pro gramming message rd 10 CR it reads data from the GPIB until it receives 10 bytes of data the END message or an eos byte Let s say the GPIB MAC receives END with the fourth data byte The GPIB MAC then returns to you the four data bytes followed by 6 null bytes followed by an ASCII 4 and lt CR gt lt LF gt A null byte is decimal 0 You should always read back count bytes of data from the serial port then look at the remaining bytes to determine how many of the count bytes were read from the GPIB Refer to the example at the end of this description The GPIB MAC aborts the GPIB read and records the EABO error if at any time during the GPIB read the time limit set for YO functions expires This limit is 10 seconds unless you use tmo to change it If the GPIB MAC is CIC rd will cause the GPIB MAC to address itself to Listen if it is not already addressed If you specify the address of the Talker the GPIB MAC will also address that device to Talk If you do not specify the address of the Talker the GPIB MAC will assume that the Talker has already been addressed The GPIB MAC then places itself in Standby Controller state with ATN off and remains there after the read operation is completed If you specify an address the GPIB MAC must be CIC to perform the addressing 59 SECTION FOUR
80. ontroller caddr Change the GPIB Address of the GPIB MAC clr Clear Specified Device cmd Send GPIB Commands echo Echo Characters Received from Serial Port eos Change Disable GPIB EOS Termination Mode eot Enable Disable END Message on GPIB Writes gts Go from Active Controller to Standby idMAC Identify System ist Set or Clear Individual Status Bit loc Go to Local onl Place the GPIB MAC Online Offline pct Pass Control ppc Parallel Poll Configure ppu Parallel Poll Unconfigure rd Read Data rpp Request Conduct a Parallel Poll rsc Request or Release System Control rsp Request Conduct a Serial Poll rsv Request Service Set or Change Serial Poll Status Byte sic Send Interface Clear spign Ignore Serial Port Errors sre Set or Clear Remote Enable stat Return GPIB MAC Status tmo Change or Disable Time Limit trg Trigger Selected Device s wait Wait for Selected Event wrt WriteData xon Change Serial Port XON XOFF Protocol frequently used function X TABLE OF CONTENTS November 1985 National Instruments 93 APPENDIX A Multiline Interface Messages 97 APPENDIX B Status Information 97 Status Bits 100 GPIB Error Codes 103 Serial Port Error Codes 105 APPENDIX C Changing from 115 VAC to 230 VAC 107 APPENDIX D Operation of the GPIB 107 Types of Messages 107 Talkers Listeners and Controllers 108 System Controller and Active Controller 109
81. ort r thePort portRect OffsetRect amp r r left r top InsetRect amp r r bottom r top 2 r right r left 2 TextBox txt long strlen txt hr teJustCenter FrameRect amp r for pause TickCount 60 TickCount lt pause 131 APPENDIX I SERIAL PORT SAMPLE PROGRAM Product User Comment Form National Instruments encourages you to give us your comments on the clarity and accuracy of the documentation supplied with its products This information helps us continue providing high quality products to meet your needs Did you find deficiencies Please comment on the completeness clarity and organization Did you find errors in the manual If so please give the page number and a description of the error Thank you for your help Name Title Company Name Number amp Street City State amp Zip Phone __ Mail to Technical Publications National Instruments 12 109 Technology Blvd Austin TX 78727 GPIB MAC
82. ples 1 PRINT 1 rsc 1 2 PRINT 1 rsc 0 3 PRINT 1 rsc National Instruments Enable GPIB MAC to be system controller Disable system control What is the current system controller status response 0 lt CR gt lt LF gt GPIB MAC is not the System Controller 64 SECTION FOUR FUNCTIONS November 1985 National Instruments rsp Request Conduct a Serial Poll rsp Syntax Purpose Remarks Serial Poll function rsp alist lt CR gt You use rsp if you wish to conduct a serial poll to obtain device specific status information from one or more devices The argument alist is a list of addrs which are separated by commas or spaces addrs are device addresses that specify the GPIB addresses you wish to poll A device address consists of a primary address and an optional secondary address The secondary address is separated from the primary address by a plus sign Only the lower five bits of each address are significant These bits may be in the range from 0 through 30 for both the primary and the secondary address Therefore the binary value 01100010 decimal 98 is interpreted as decimal 2 The following examples all specify a primary address of 0 and a secondary address of 2 The listen address is 32 the talk address is 64 and the secondary address is 2 or 98 which are equivalent 0 2 or 0498 or 324 98 or 0 x62 rsp serially polls the specified devices to obtain thei
83. ples 1 PRINT 1 SRE 1 Set REN 2 PRINT 1 sre 0 Unassert REN 74 SECTION FOUR FUNCTIONS November 1985 National Instruments stat Return GPIB MAC Status stat General Use function Syntax stat c n zCR Or stat c s lt CR gt Or stat c n s lt CR gt Purpose You use stat to obtain the status of the GPIB MAC to see if certain conditions are currently present You use stat most often to see if the previous operation resulted in an error Remarks You should use stat frequently in the early stages of your of your program development when your device s responses are likely to be unpredictable The GPIB MAC responds with status information in a form depending on the mode or combination of modes you chose n indicates that the status information will be returned as numeric strings s indicates that the status information will be returned in symbolic format i e as mnemonic strings c specifies that the status will be returned after each programming message eliminating the need to call Stat after each programming message Normally you use s only when you are debugging your code and you want to print the mnemonic for each piece of status information The status information returned by the GPIB MAC contains four pieces of information the GPIB MAC status a gpib error code a serial error code and a count The GPIB MAC returns a lt CR gt lt LF gt following each piece of the response 75 SECTION
84. r IFC to make itself CIC If you passed control to some other GPIB device control must be passed back to you or you must send IFC to make yourself CIC before making this call Otherwise the ECIC error will be posted If you do not give an alist and the GPIB MAC is not CIC it assumes it will be addressed by the controller If you do not give an alist and the GPIB MAC is CIC it addresses itself as talker and assumes the listeners are already addressed The first part of this programming message up to CR is buffered meaning the GPIB MAC will not act upon it until it receives CR The string that follows the first line is piped to the GPIB non buffered This allows you to send a string larger than the GPIB MAC s internal buffer with one programming message The GPIB MAC aborts the GPIB write if it receives Device Clear or Selected Device Clear and its Listen Address The GPIB MAC aborts the GPIB write and records the EABO error if at any time during the GPIB write the time limit set for I O functions expires This 89 SECTION FOUR FUNCTIONS November 1985 National Instruments limit is 10 seconds unless you use tmo to change it The GPIB MAC also aborts the wrt and records the ENOL error if there are no addressed Listeners when it begins to send data Refer also to tmo for timeout information to Appendix B for more error information and to spign for serial port error handling information Examples 1 PRINT
85. r status bytes If bit 6 the hex 40 or RQS bit of a device s response is set its status response is positive i e that device is requesting service Before rsp completes all devices are unaddressed 65 SECTION FOUR FUNCTIONS November 1985 National Instruments The interpretation of each device s response other than the RQS bit is device specific For example the polled device might set a particular bit in the response byte to indicate that it has data to transfer and another bit to indicate a need for reprogramming Consult the device documentation for interpretation of the response byte Each device s serial poll response byte is returned as a numeric string giving the decimal value of the byte followed by lt CR gt and lt LF gt If a device does not respond in the timeout period the GPIB MAC returns string 1 and records the EABO error The time limit is set to 1 10 second unless you called tmo to change it Each response corresponds directly to an address you specify therefore there are exactly as many lines of responses including 1 as the number of addresses you specify If you call rsp and the GPIB MAC is not CIC it attempts to become CIC If it cannot become CIC it records the ECIC error Refer to Appendix B for more information If this is the first function you call that requires GPIB controller capability and you have not disabled System Controller capability with rsc the GPIB MAC sends Inte
86. r the serial port if its serial receive buffer is almost full This tells the sender to stop sending data When the GPIB MAC serial port receive buffer has room to safely receive more bytes the GPIB MAC sends XON over the serial port This tells the sender to begin sending data again You should use XON XOFF when you are transferring large amounts of data at a high baud rates Without it you are in danger of overflowing the GPIB MAC internal buffer or your Macintosh s internal buffer 91 SECTION FOUR FUNCTIONS November 1985 National Instruments The power on default is that XON XOFF for both cases is disabled If you call xon without an argument the GPIB MAC returns to you the current settings I protocol enabled O protocol disabled Examples 1 PRINT 1 XON 1 1 Enable GPIB MAC XON XOFF protocol for TX and RX 2 PRINT 1 XON 0 1 Disable protocol on TX enable protocol on RX 3 PRINT 1 XON Return current settings response 0 1 lt CR gt lt LF gt transmit protocol disabled receive protocol enabled 4 PRINT 1 XON 0 Disable protocal on RX keep current setting on TX 92 SECTIONFOUR FUNCTIONS November 1985 National Instruments Appendix A Multiline Interface Messages The following tables are multiline interface messages Sent and Received with ATN TRUE 93 APPENDIX A MULTILINE INTERFACE MESSAGES November 1985 National Instruments Multiline Interface Messag
87. racters will not be echoed until this command has been completely processed i e the next programming message will be echoed If you call echo without an argument the GPIB MAC returns the current setting Examples Note The following examples show commands as you would enter them at a terminal 1 echo 1 lt CR gt Turn on character echoing 2 ECHO O lt CR gt Disable character echoing 3 echo lt CR gt What is the current echo status response 0 lt CR gt lt LF gt character echo is disabled 38 SECTION FOUR FUNCTIONS November 1985 National Instruments eos Change Disable GPIB EOS Termination Mode eos Initialization function Syntax eos R X B eoschar lt CR gt or eos D lt CR gt Purpose You use eos at the beginning of your program if you wish to use an eos mode when you transfer data to and from the GPIB eos tells the GPIB MAC when to stop reading information from the GPIB eos also enables the GPIB MAC to tell other devices that it is finished writing information to the GPIB eos defines a specific character end of string EOS to be recognized as a string terminator Remarks The arguments R X B and D specify GPIB termin ation methods They enable or disable the corresponding eos mode If a particular letter is specified the corres ponding eos mode is enabled If it is not specified the corresponding eos mode is disabled eoschar is a numeric string which represents a single ASC
88. ram This appendix contains a sample program that contains code to control the serial port of the Macintosh from a C program It is provided to demonstrate how to write your own serial I O routines if the language you are using does not already provide them Sample Program send c g 30 85 JR Send file out modem port fast bkz 0 sts 2 Purpose This program is designed to send a text file containing commands and data to the GPIB MAC The program was compiled with Manx Aztec C 68K 106 F The data file is read into memory once then sent to the serial driver in a loop Programming languages such as MacBasic and MacPascal have too much overhead to send data faster than 19200 baud include lt quickdraw h gt include pb h File amp Device managers include stdio h Standard I O include lt serial h gt include lt memory h gt include event h include lt inits h gt InitFonts include lt packages h gt File Package include textEdit h textbox define FALSE 0 main0 short refAOut refAIn port reference numbers char 9 pBufIn input buffer int rc result code int inLen 1 13 input buffer size 127 APPENDIX I SERIAL PORT SAMPLE PROGRAM November 1985 National Instruments InitGraf amp thePort InitFonts initialize Fonts call OS Event Mngr to discard events FlushEvents everyEv
89. rface Clear IFC to make itself CIC It also asserts Remote Enable If you passed control to some other GPIB device control must be passed back to you or you must send IFC to make yourself CIC before making this call Otherwise the ECIC error will be posted If you call rsp without an argument the GPIB MAC records the EARG error Refer also to tmo for timeout information 66 SECTION FOUR FUNCTIONS November 1985 National Instruments Example 67 PRINT 1 rsp1 28 5 9 Poll 3 devices response 42 lt CR gt lt LF gt device 9 did not respondwithin 30 lt CR gt lt LF gt the timeout period 1 lt CR gt lt LF gt DIM SPR amp 2 Read 3 responses from serial port buffer FOR I 0 to 2 LINE INPUT 1 RESP Store each serial poll response in SPR D VAL RESP the array SPR IF SPR I 1 THEN GOSUB 1000 1000 is an error routine NEXTI REM Code will now interpret serial poll responses SECTION FOUR FUNCTIONS November 1985 National Instruments rsv Request Service Set or Change Serial Poll Status Byte rSv Serial Poll function Syntax rsv spbyte CR Purpose You use rsv if the GPIB MAC is not GPIB Controller and you wish to request service from the Controller using the Service Request SRQ signal The GPIB MAC will provide a user defined status byte when the Controller serially polls it Remarks The argument spbyte is a numeric string specifying the decimal value o
90. roblem Just call 800 53 1 GPIB 800 531 5066 outside Texas 800 IEEE 488 inside Texas between the hours of 8 00 a m and 5 00 p m Central Time Now look over the next few pages at how the manual is organized and then at the Table of Contents so that you will be familiar with the complete contents for future reference vii PREFACE November 1985 National Instruments Organization of the Manual Section One gives brief introductions to the GPIB MAC and the IEEE 488 Section Two contains the installation and configuration steps Section Three explains how to program the GPIB MAC Section Four gives a detailed description of each function The function descriptions are arranged in alphabetical order and each contains the syntax and purpose of the functions and examples Appendix A contains a table of multiline interface messages Appendix B lists status information Appendix C shows how to change the operating voltage from 115 to 230 Appendix D describes the operation of the GPIB Appendix F gives answers to common questions Appendix F explains the use and operation of Parallel Polls Appendix G gives additional detail on setting switches on the GPIB MAC Appendix H contains a sample program of general programming steps Appendix contains a sample program to control the serial port of the Macintosh from a C program vn PREFACE November 1985 National Instruments TABLE OF CON
91. rred before the timeout are not affected The timeio time limit is also the maximum amount of time the wait function waits when you call it with the TIMO bit set in the wait mask 81 SECTION FOUR FUNCTIONS November 1985 National Instruments The timesp time limit is in effect only for the rsp function If a polled device fails to respond within the amount of time indicated by timesp the GPIB MAC returns an error flag Refer to the rsp programming message If you want to change only the timeout value for serial polls a comma must precede the serial poll timeout value If you call tmo without an argument the GPIB MAC returns a numeric string representing the current timeout settings It records the EARG error if you specify a time value outside the range 00001 to 3600 The assignment made by this function remains in effect until you call tmo again call onl or turn off the GPIB MAC Examples 1 PRINT 1 tmo 30 Set timeout for I O operations to 30 seconds leave serial poll timeout unchanged 2 PRINT 1 TMO Print current timeout settings response 30 1 lt CR gt lt LF gt 3 PRINT 1 tmo 1 Set serial poll timeout for one second leave I O timeout unchanged 82 SECTION FOUR FUNCTIONS November 1985 National Instruments trg Trigger Selected Device s trg Bus Management function Syntax Purpose Remarks trg alis t lt CR gt You use trg to trigger the specified devic
92. s interpreted as decimal 2 The following examples all specify a primary address of 0 and a secondary address of 2 The listen address is 32 the talk address is 64 and the secondary address is 2 or 98 which are equivalent 0 2 or 02 98 or 324 98 or 0 x62 The argument ppr is an integer string between and 8 specifying the data line on which to respond The argument s is either 0 or and is interpreted along with the value of the device s individual status bit to determine whether to drive the line true or false Each group of addr ppr s may be separated by either a comma or space just as any list of arguments 54 SECTION FOUR FUNCTIONS November 1985 National Instruments If you call ppc without an argument the GPIB MAC records the EARG error If this is the first function you call that requires GPIB controller capability and you have not disabled System Controller capability with rsc the GPIB MAC sends Interface Clear IFC to make itself CIC It also asserts Remote Enable If you passed control to some other GPIB device control must be passed back to you or you must send IFC to make yourself CIC before making this call Otherwise the ECIC error will be posted The GPIB MAC takes the arguments ppr and s and constructs the appropriate parallel poll enable PPE message for each addr specified When addr is the address of the GPIB MAC the GPIB MAC programs itself to respond to a parallel poll by setting i
93. st send IFC to make yourself CIC before making this call Otherwise the ECIC error will be posted If you call loc without alist and the GPIB MAC is System Controller the GPIB MAC returns all devices to local mode by unasserting REN and asserting it again If you call loc without alist and the GPIB MAC is not System Controller the GPIB MAC records the ESAC error Refer to Appendix B for more error information 1 PRINT 1 loc 6 22 4 23 7 Put 3 devices in local mode 2 PRINT 1 LOC Put all devices in local mode frequently used function 49 SECTION FOUR FUNCTIONS November 1985 National Instruments onl Place the GPIB MAC Online Offline onl Initialization function Syntax onl bool lt CR gt Purpose Remarks You use onl to disable communications between the GPIB MAC and the GPIB or to reinitialize the GPIB MAC characteristics to their default values If the argument bool is 1 the GPIB MAC places itself online If the argument bool is 0 the GPIB MAC places itself offline By default the GPIB MAC powers up online is in the Idle Controller state and configures itself to be the System Controller If you call onl without an argument the GPIB MAC returns the current status of the GPIB MAC which is 0 if the GPIB MAC is offline and 1 if the GPIB MAC is online Placing the GPIB MAC offline may be thought of as disconnecting its GPIB cable from the other GPIB devices Placing the GPIB M
94. the Macintosh using Microsoft BASIC to draw a circle using an HP 7475A Plotter Getting Ready to Program Before you start programming determine the serial port settings you will use The settings for this example are 9600 baud rate 8 data 1233 APPENDIX H SAMPLE PROGRAM November 1985 National Instruments bits 1 stop bit and no parity Set the back panel switches on the GPIB MAC as follow Then connect the serial cable to the serial port of your Macintosh and to the GPIB MAC Connect the GPIB cable to your device and the GPIB MAC Turn the power switch of the GPIB MAC to On Programming Steps Step 1 stat Function In BASIC before reading or writing to the serial port a device must be opened Place the following BASIC statement at the beginning of your program to open and configure the serial port COM1 and name it device 1 OPEN COM1 9600 n 8 1 as 1 Note that you will now use PRINT 1 to redirect strings to the serial port Now send the stat function if you want status information returned after every programming message To do this include the following code in your program PRINT 1 stat c n After you send this programming message you can expect four lines of data at the serial port each line is terminated by lt CR gt lt LF gt For now call a subroutine to check the status You can write this later For now add the line GOSUB status 124 APPENDIX H SAMPLE PROGRAM November 1
95. the end of a transmission 21 SECTION THREE PROGRAMMING THE GPIB MAC November 1985 National Instruments The GPIB MAC always terminates GPIB rd operations on the END message Using the eos and eot functions you may change the other default GPIB read and write termination methods Default Settings The following tables list power on characteristics of the GPIB MAC and the functions you can use to change those characteristics SERIAL PORT CHARACTERISTICS Characteristic Power on Value echo bytes to serial port no ignore serial port errors yes send XON XOFF no recognize XON XOFF no GPIB CHARACTERISTICS Characteristic power on Value primary secondary address pad 0 sad none end of string modes none send END on writes ye ist bit setting 0 GPIB MAC is System Controller yes VO timeout 10 sec serial poll timeout sec List of Functions by Group Function echo spign xon xon Function caddr eos eot ist TSC tmo tmo The GPIB MAC functions are divided into three main groups GPIB functions Serial Port functions and General Use functions 22 SECTION THREE PROGRAMMING THE GPIB MAC November 1985 National Instruments GPIB Functions The GPIB functions are divided into subgroups as shown The subgroups are listed with the most frequently used groups first Often the I O and bus management functions are the only ones you need 23 I O FUNCTIONS Function Purpose RD count address Read data
96. the string so a carriage return is not placed there explicitly To send more than one programming message per PRINT statement embed a CR denoted by CHR 13 or lt LF gt denoted by CHR 10 in the statement For example to send the two programming messages send interface clear and send remote enable you could use either of these two sequences PRINT 1 sic PRINT 1 sre 1 Or PRINT 1 sic CHR 13 sre 1 For all examples the communications port has been assigned to file number 1 1 by the BASIC OPEN COM statement SECTION FOUR FUNCTIONS November 1985 National Instruments 6 28 It is necessary for you to send only enough characters of the function name to distinguish it from other functions Those characters are shown in boldface in the syntax portion of each function description I O and bus management functions meet most of your needs In the descriptions that follow these frequently used functions are marked with an asterisk SECTION FOUR FUNCTIONS November 1985 National Instruments cac Become Active Controller cac Low level Controller function Syntax cac bool lt CR gt Purpose Remarks You use cac to change the GPIB MAC from Standby Controller to Active Controller and when the I O and bus management functions do not meet the needs of your device cac allows you more precise control over the GPIB than the I O and bus management functions If the
97. tically puts the device in remote program mode You then use loc to return devices to local program mode Remarks The argument alist is a list of addrs separated by commas or spaces addrs are device addresses that specify the GPIB addresses of the devices you wish to return to local mode A device address consists of a primary address and an optional secondary address The secondary address is separated from the primary address by a plus sign Only the lower five bits of each address are significant These bits may be in the range from 0 through 30 for both the primary and the secondary address Therefore the binary value 01100010 decimal 98 is interpreted as decimal 2 The following examples all specify a primary address of 0 and a secondary address of 2 The listen address is 32 the talk address is 64 and the secondary address is 2 or 98 which are equivalent 0 2 or 0 98 or 32498 or 0 x62 If you call loc with alist the GPIB MAC places the specified device s in local mode using the Go To Local GTL command 48 SECTION FOUR FUNCTIONS November Examples 1985 National Instruments If this is the first function you call that requires GPIB controller capability and you have not disabled System Controller capability with rsc the GPIB MAC sends Interface Clear IFC to make itself CIC It also asserts Remote Enable If you passed control to some other GPIB device control must be passed back to you or you mu
98. tions Width 216 9 mm 8 5 inches Height 88 4 mm 3 5 inches Depth 330 2 mm 13 0 inches Weight 5 25 pounds Electrical Specifications The GPIB MAC is designed to operate under the following electrical specifications Power 115 volts AC or 230 volts AC 50 60 Hz 20 VA Typical Current 09 amps AC Fuse Type 115 volts AC use 1 4 amp Fast 230 volts AC use 1 8 amp Fast 6 SECTION ONE INTRODUCTION November 1985 National Instruments Section Two Installation and Configuration Use this section to install and configure the GPIB MAC Then read Sections Three and Four to learn about how to program the GPIB MAC Inspection Before you install the GPIB MAC inspect the shipping container and its contents for damage If damage appears to have been caused in shipment file a claim with the carrier Retain the packaging material for possible inspection or for reshipment If the equipment appears to be damaged do not attempt to operate it Contact National Instruments for instructions Installation There are four basic steps to installing the GPIB MAC 1 Verify voltage requirements 2 Configure GPIB MAC rear panel switches 3 Connect cables 4 Turn power switch to On Voltage Requirements The GPIB MAC is shipped with the internal voltage selector switch configured to operate on a standard 115 VAC power line If your setup requires 230 VAC refer to Appendix C to learn how to open the box to change the voltage selec
99. tor switch 7 SECTION TWO INSTALLATION AND CONFIGURATION November 1985 National Instruments Configure the GPIB MAC Rear Panel Switches Configure the GPIB MAC by setting the switches of the 9 pin rear panel DIP switch The following figure shows the switches labeled for factory use only 7 or 8 bit word length one or two stop bits odd even or no parity and baud rate Ww gt ul 0 OFF 1 ON N oele A FACTORY USE pup o o x cnl BAUD RATE WORD LENGTH 000 300 STOP BITS 001 1200 PARITY 010 2400 011 4800 100 9600 101 19 2K 110 38 4K 111 57 6K GPIB MAC DIP Switch itch l and 2 r Switch 1 and 2 are for factory use only and should always be positioned in the off position as shown below Factory Use Only 8 SECTION TWO INSTALLATION AND CONFIGURATION November 1985 National Instruments Switch 3 Word Length Configure the GPIB MAC for a serial word length of 7 or 8 bits by setting switch 3 The off position indicates 7 bits the on position PO 7 bit Word Length dUHRB 8 bit Word Length 9 SECTION TWO INSTALLATION AND CONFIGURATION November 1985 National Instruments Switch 4 Stop Bits Configure the GPIB MAC for a stop bit length of 1 or 2 bits by setting switch 4 The off position indicates 1 bit the on position indicates 2 415 2 Stop Bits 10 SECTION TWO INSTALLATION AND CONFIGURATION November 1985 National Instruments Switches 5 and 6 Par
100. tring identifies the number of bytes of RAM in the GPIB MAC Example PRINT 1 idMAC Get system identification response GPIB MAC Rev A 0 lt CR gt lt LF gt c 1985 National InstrumentscCR LF 2K bytes RAM lt CR gt lt LF gt 46 SECTION FOUR FUNCTIONS November 1985 National Instruments ist Set or Clear Individual Status Bit ist Parallel Poll function Syntax ist bool CR Purpose You use ist when the GPIB MAC participates in a parallel poll that is conducted by another device that is Active Controller Remarks If the argument bool is 1 the GPIB MAC s individual status bit is set to 1 If the argument bool is 0 the GPIB MAC s individual status bit is cleared The power on default is 0 If you call ist without an argument the GPIB MAC returns the value of its individual status bit Refer also to ppc and Appendix F Examples 1 PRINT 1 ist 1 Set ist to 1 2 PRINT 1 IST 0 Clear ist to 0 3 PRINT 1 ist What is ist set to response 0 lt CR gt lt LF gt ist is currently 0 47 SECTION FOUR FUNCTIONS November 1985 National Instruments loc Go to Local loc Bus Management function Syntax loc alist CR Purpose You use loc to put a device in local program mode In this mode you can program the device from its front panel Since a device must usually be placed in remote program mode before it can be programmed from the GPIB the GPIB MAC automa
101. ts local poll enable Ipe message to the value specified Refer also to ist ppu rpp and to Appendix F on parallel polling Example 55 PRINT 1 PPC 18 23 8 0 23 10 7 1 Configure 2 devices for parallel poll PRINT 1 RPP Conduct a Parallel poll of 2 devices configured above response 192 lt CR gt lt LF gt both devices responded positively LINE INPUT 1 RESP PPR VAL RESP Assign parallel poll response to integer variable SECTION FOUR FUNCTIONS November 1985 National Instruments ppu Parallel Poll Unconfigure ppu Syntax Purpose Remarks Parallel Poll function ppu alist CR You use ppu if you are performing parallel polls and you wish to prevent certain devices from responding The argument alist is a list of addrs which are separated by commas or spaces addrs are device addresses that specify the GPIB addresses of the device or devices to be disabled from parallel polls A device address consists of a primary address and an optional secondary address The secondary address is separated from the primary address by a plus sign Only the lower five bits of each address are significant These bits may be in the range from 0 through 30 for both the primary and the secondary address Therefore the binary value 01100010 decimal 98 is interpreted as decimal 2 The following examples all specify a primary address of 0 and a secondary address of 2 The list
102. tus ERR TJMO END 32768 The ERR bit is set in status following any call that results in an error the particular error may be determined by examining the gpib error and serial error values The ERR bit is cleared following any call that does not result in an error Note By examining this bit you may check for an error condition after each call An error made early in your application program may not become apparent until a later instruction At that time the error can be more difficult to locate 16384 The TIMO bit specifies whether a timeout has occurred The TIMO bit is set in the status word following a call to wait if the TIMO bit of the wait mask parameter is also set and if the wait has exceeded the time limit value that is set by the tmo call The TIMO bit is also set following a call to any of the I O functions e g rd wrt and cmd if a timeout occurs during a call The TIMO bit is cleared in the status word in all other circumstances 8192 The END bit specifies whether the END or EOS message has been received The END bit is set in the status word following a rd function if the END or EOS message was 97 APPENDIX B STATUS INFORMATION November 1985 National Instruments SRQI detected during the read While the GPIB MAC is performing a shadow handshake as a result of the gts function any other function call may return a status word with the END bit set if the END or EOS message occurred before or

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