Service Request; Rqs Mask; Clearing The Service Request Message - HP 8642A Operating Manual

Model 8642A/B Operation
SERVICE REQUEST
Overview 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).
RQS MASK 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 Figure 3-4 on the following page.) Bits 0
through 5 and 7 of the Status Byte are logically ANDed 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 t u r n - o n 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 Local Mode:
Select RQS MASK ( [ SHIFT ) [ INT ) ), the decimal equivalent of the binary 8-bit byte
and any terminator (such as ["HZ UVn )•
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 1000001 1 (decimal 131).
Set the mask value to:
Local operation:
Remote operation:
binary 10000011 = decimal 131
RQS MASK
(rsHim r w i ) Q J CXI CD i
HZ
uv i
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 mask. If the condition which caused SRQ to be pulled has been resolved,
the Service Request message 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