Agilent Technologies HP 54601B Specifiche Scaricare il pdf (Pagina 69)

Serial Poll

This oscilloscope 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

The service request can used by conducting a serial poll of all instruments on

the bus. For this procedure, assume that there are two instruments on the

bus: an oscilloscope 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 Agilent BASIC is

Stat=SPOLL(707). The address 707 is the address of the oscilloscope 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 GPIB 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:

1 Enable interrupts on the bus. This allows the controller to “see” the

SRQ line.

2 If 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.

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, then 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.

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.

Status Reporting

Serial Poll

6–6

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Agilent Technologies HP 54601B Specifiche Pagina 69