Serial poll
This logic analyzer supports the IEEE 488.1 serial poll feature. When a serial
poll is requested of the instrument, the RQS bit is returned on bit 6 of the
status byte.
Using Serial Poll
The service request can be used by conducting a serial poll of all instruments
on the bus. For this procedure, assume that there are two instruments on the
bus: a logic analyzer at address 7 and a printer at address 1. It is assumed
that you are operating on Interface Select Code 7.
The program command for serial poll using HP BASIC is Stat=SPOLL(707).
The address 707 is the address of the logic analyzer in this example. The
command for checking the printer is Stat=SPOLL(701) because the address
of that instrument is 01 on bus address 7. This command reads the contents
of the HP-IB Status Register into the variable called Stat. At that time bit 6 of
the variable Stat can be tested to see if it is set (bit 6=1).
You can conduct the serial poll operation using the following steps:
1
Enable interrupts on the bus. This allows the controller to “see” the
SRQ line.
2
If the SRQ line is high (an instrument is requesting service) then
check the instrument at address 1 to see if bit 6 of its status register is
high.
3
Disable interrupts on the bus.
4
To check whether bit 6 of an instrument’s status register is high, use
the following command line.
IF BIT (Stat, 6) then
5
If bit 6 of the instrument at address 1 is not high, check the
instrument at address 7 to see if bit 6 of its status register is high.
6
As soon as the instrument with status bit 6 high is found, check the
rest of the status bits to determine what is required.
Status Reporting
Serial poll
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