Service Request; Service Request; Overview; Rqs Mask - HP 8642A Operation And Calibration Manual

Synthesized signal generator
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Model 864 2A/B
Operation
Overview
RQS MASK
~
SERVICE REQUEST
The Signal Generator uses its internal Status Byte and a Request Service Mask Byte (RQS
mask that you set) to determine whether to issue a Service Request (SRQ bus line true).
The RQS mask is an 8-bit byte that you can set to define which bits of the Status Byte
will be allowed to cause a service request. (See f'igure 3-4 on the following page.) Bits 0
through 5 and 7 of the Status Byte are logically A NDed with bits 0 through 5 and 7 of
the RQS mask byte. If the resultant value is not equal to zero, the Signal Generator sets
bit 6 of the Status Byte true, which sends a Service Request (SRQ) message to the system
controller (SRQ bus line true).
At turn-on or instrument preset, the RQS mask byte is set to zero, effectively disabling or
masking all the status bits from causing a service request message.
Changing the 8-bit RQS Mask Byte
From the Remote Mode:
Send RM, the decimal equivalent of the binary 8-bit byte (a number between 0 and 255),
and the terminator,
HZ.
/)
From the Loca I Mode:
Select RQS MASK ( ( sHIFT I
O!TIJ ),
the decimal equivalent of the binary 8-bit byte
a
nd any terminator (such as
l8.f-=:gyJ ).
Example
Enable status bits 0 (End of Sweep), 1 (Hardware Error), and 7 (Parameters Changed) to
cause a service request (SRQ bus line true) by unmasking those bits; that is, set the Signal
Generator's RQS mask to binary 10000011 (decimal 131).
Set the mask value to:
Local operation:
Remote operation:
binary 10000011
=
decimal 131
RQS MASK ( ( SHIFT)
CITTIJ ) CD
rn
o:J
[HZ OV )
RM 131 HZ
A Service Request can be generated in either the local or remote mode. To determine
which status bit caused the serVIce request, refer to Table 3-7, HP-IB Status Byte Bit
Definitions, on page 3-30. The Status Byte can be read only by doing a serial poll via
HP-IB
(refer to page 3-29).
Clearing the
Service Request
Message
The Service Request message can be cleared
by
masking the "set" bits in the Status Byte
using the RQS
ma~k.
If the condition which caused SRQ to be pulled has been resolved,
the Service
RCqUClit
lllessage can be cleared with any of the following actions for clearing
the Status Byte:
Sending Clear Status (CS).
Sending Instrument Preset (IP).
Sending Device Clear or Selected Device Clear.
Switching Power from Standby to On.
Resetting the individual "set" bits. (Refer to Table 3-7 on page 3-30.)
3-27

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