HP Sander 16500C 7–8, Serial Poll, the BASIC statement, Using Serial Poll (HP-IB), 1Enable interrupts on the bus, 2Disable interrupts on the bus

Status Reporting

Serial Poll

Serial Poll

The HP 16500C Logic Analysis System supports the IEEE 488.1 serial poll feature. When a serial poll of the instrument is requested, the RQS bit is returned on bit 6 of the status byte.

Using Serial Poll (HP-IB)

This example will show how to use the service request by conducting a serial poll of all instruments on the HP-IB bus. In this example, assume that there are two instruments on the bus: the Logic Analysis System at address 7 and a printer at address 1.

The program command for serial poll using HP BASIC 6.2 is

Stat = SPOLL(707). The address 707 is the address of the Logic Analysis System in the 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).

The serial poll operation can be conducted in the following manner:1Enable interrupts on the bus.This allows the controller to see the SRQ line.2Disable interrupts on the bus.

3If the SRQ line is high (some instrument is requesting service) then check the instrument at address 1 to see if bit 6 of its status register is high.

4To check whether bit 6 of an instruments status register is high, usethe BASIC statement IF BIT (Stat, 6) THEN

5If bit 6 of the instrument at address 1 is not high, then check the instrument at address 7 to see if bit 6 of its status register is high.

6As soon as the instrument with status bit 6 high is found check the rest of the status bits to determine what is required.

The SPOLL(707) command causes much more to happen on the bus than simply reading the register. This command clears the bus automatically, addresses the talker and listener, sends SPE (serial poll enable) and SPD (serial poll disable) bus commands, and reads the data. For more information about serial poll, refer to your controller manual and programming language reference manuals.

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