-SCS Parameter Analyzer Reference Manual Section 9: Keithley External Control Interface (KXCI)
4200A-901-01 Rev. C / February 2017 9-55
Bit B1, Syntax Error
This bit sets (1) when an invalid command string is sent to the 4200A-SCS. Any of the following
actions will clear (0) bit B1:
• When the 4200A-SCS is serial polled.
• When a device clear command (DCL or SDC command) is sent to the 4200A-SCS.
Bit B4, Busy
This bit is set (1) while a measurement is being performed. It will clear (0) when the measurement is
completed.
Bit B6, RQS (request for service)
This bit sets (1) whenever bit B1 (syntax error) sets. If service request for data ready is enabled (DR1
asserted), bit B6 will set whenever bit B0 (data ready) sets. If service request for data ready is
disabled (DR0 asserted), bit B6 will not be affected by bit B0.
Bit B6 remains set until one of the following actions occur:
• Clears (0) when the 4200A-SCS is serial polled.
• Clears (0) when a device clear command (DCL or SDC command) is sent to the 4200A-SCS.
When bit B6 sets, the SRQ (service request) indicator on the KXCI user interface turns on. It turns off
when B6 is cleared.
Serial polling
The serial poll enable (SPE) and serial poll disable (SPD) general bus command sequence is used to
serial poll the 4200A-SCS. Serial polling reads the status byte. Generally, the controller uses the
serial polling sequence to determine which of several instruments has requested service with the
SRQ line. However, the status byte of the 4200A-SCS may be read to determine when an operating
condition has occurred.
If you try to get data before all the measurements in a test are completed, a GPIB error will occur. To
prevent this, you can use serial polling in a program fragment to monitor the data ready bit (B0) of the
status byte. When B0 sets to indicate that data is ready, the program will proceed to obtain the
measurement data.
After the source-measure testing process is triggered to start (that is, ME1 sent to start a sweep), the
following C language programming statement serial polls the instrument.
spoll(addr, &poll, &status);
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