Download Manual - Phase Matrix

5/PROGRAMMING
bit7
6
5
4
(128) (64) (32) (16)
3
(8)
2
(4)
1
(2)
bit0
(1)
Input buffer empty
IRQ bit (Master Summary Status)
Error condition
Overload
Gate on
Search on
Signal found
Valid measurement result (data) ready
Figure 5-1. Status Byte Structure
SERVICE REQUEST MASK
The counter can be instructed to send an interrupt, by setting the SRQ line on the GPIB, when any
ORed combination of the bits in the status byte are set. This is done by sending the counter a
service request mask.
For example, to instruct the counter to generate an SRQ whenever it has valid data available or an
error condition exists, send the following service request mask:
Send 0, 18, “SRQMASK 33", NLend
This would tell the counter to generate an SRQ whenever bit 0 and bit 5 of the status byte are set.
Since bit 0 corresponds to valid measurement result ready and bit 5 corresponds to an error
condition, the counter would generate an SRQ whenever either an error condition exists or a valid
measurement is available.
The following items should be included in any program using the SRQ feature:
1. Tell the counter when to generate an SRQ. That is, tell the counter which events should
generate an SRQ. This is done using the SRQMASK command.
2. Tell the controller to monitor the SRQ line on the GPIB. The SRQ is a maskable interrupt and
the controller needs to know if it should respond to the interrupt.
3. Tell the controller what to do when it receives an SRQ interrupt.
4. Serial poll the counter after an SRQ is generated to clear the interrupt. When the counter
generates an SRQ it sets bit 6 in the status byte. Serial polling the instrument clears the SRQ
bit and allows the instrument to generate a new SRQ upon the next occurrence of the
conditions specified in the SRQ Mask.
5. It may also be necessary to clear the SRQ register in the controller. Consult your manual on
the controller for more information on clearing the SRQ register in the controller.
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