HP 8901B Operation And Calibration Manual page 148

Model 8901B Operation
SRQ
MASK (Special Function 22)
Overview. Special F'unction 22 is used to set the bits of the SRQ Mask. The set SRQ Mask bits
unmask the bits of the Status Byte. At power-up or Instrument Preset, all Status Byte bits are masked
except the HP-IB Error Code bit. The appropriate SRQ Mask bits must be set to
1
by the operator
to unmask any other Status Byte bit. Refer to Figure 3-4, "Issuing a Service Request" for a graphic
example of these relationships.
NOTE
Bit
1
of the SRQ
M a s k
is permanently set to
1;
therefore, an HP-IB code
error will ALWAYS generate a Service Request message. This means that
the Service Request message CANNOT be disabled.
Setting
the SRQ Mask.
Only bits 0, 2, 3, 4 and 5 can be set. Bit 1 (weighk2) is permanently set.
To
set the SRQ Mask bits and unmask the Status Byte bits which you want to cause the Service
Request Message to be issued
0
Sum
the weights of the desired conditions using Table 3-9 below. Use this sum as the suffix of
Special Function 22.
NOTE
Since Bit 1 (HP-IB Code Error)
is
permanently enabled, if the weight
is
not summed in, it will be assumed by the instrument, for example 22.0SP
is
equivalent to 22.2SP.
0
Enter the special function code (and suffix) via the front panel, then select SPCL; or, for remote
operation, enter 22.<suffix>SP.
Example. To set the SRQ Mask so that the Modulation Analyzer will issue a Service Request message
for all conditions except Data Ready, first compute the Special Function suffix by summing the
corresponding weights.
4
+
8
+
16
+
32 = 60
Key in 22.60SP. (22.62SP would also work because of the permanently set HP-IB Error Code bit.)
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