Agilent Technologies 4294A Service Manual download pdf (Page 475)

Appendix B 475

Status Reporting System

General Status Register Model

B. Status Reporting System

2. Chapter Title 3. Chapter Title

4. Chapter Title

5. Chapter Title

Event register

Reflects the correspondent condition of the 4294A (e.g. occurrence of an event) as a bit

status. These bits monitor the changing 4294A’s state continuously and change bit status

when the condition (e.g. change bit status to “1” if a specific event occurs) for each bit is

met. You cannot change bit status by GPIB command.

4294A has the following event registers:

• Instrument Event Status Register (See Table B-3 for details)

• Standard Event Status Register (See Table B-2 for details)

• Operation Status Event Register (See Table B-4 for details)

Enable register

Setting the enable register allows you to specify event register bits which can set “1” to the

summary bit of the status byte register when an event occurs. The register bits work like

mask bits; setting “1” to an enable register will enable a corresponding bit in the event

For example, when you want to set “1” the summary bit in the status byte register by a

specific register condition, set the corresponding enable register to “1”.

Status byte register

If the enabled event register is set to “1”, a corresponding bit of the status byte register is

also set to “1”. This register also indicates the output queue and SRQ status.

The value of the status byte register can be read by using the “*STB?” command on page

261 or serial poll (SPOLL statement in HP BASIC) from the controller. The “*STB?” sets

the analyzer to remote mode. On the other hand, the SPOLL statement in HP BASIC reads

the status byte register value directly without the instrument being set to remote. Therefore,

you can continue to operate front panel keys while a controller is reading the status byte

Reading the status byte register by the “*STB?” command does not affect the contents of

the status byte register. However, reading with the SPOLL statement of HP BASIC will

clear the RQS bit in the status byte register.

Table B-1 shows the contents of the status byte register for the 4294A. A serial poll

initiated by using the SPOLL command reads bit 6 of the status byte register as the RQS

bit. The

“*STB?” command reads bit 6 as the MSS bit. See Table B-1 for details on RQS

and MSS bits.

SRQ (Service Request) can be generated linking with the status byte register by setting the

service request enable register.

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Agilent Technologies 4294A Service Manual Page 475