HP 3468A Operator's Manual page 44

Status Register
The Status Register in the 3468A is used to continuously monitor seven condi-
tions within the multimeter. The figure below illustrates the Status Register and
defines each bit. The bits are set when the indicated condition occurs and will be
cleared when the INSTAT message is sent to the 3468A, except as noted.
Status Byte
The Status Byte is an eight bit byte that may be used to determine the current
status of the 3468A. The Status Byte is output from the Status Register in
response to the INSTAT command.
Bit 7 of the register will be set only if switch 3 (rear panel of the 3468A) is set to
the "UP" position and a power-on reset occurs. It is cleared when the INSTAT
message is sent to the 3468A.
Bit 6 of the Register will be set (a " 1") when the 3468A SRO Mask has been set
for certain bits, specified by bits O through 5, and when those conditions occur.
The purpose of bit 6 is that, when set, the 3468A can interrupt the controller.
However, the -hp- Model 41C/41CV does not respond to an SRO (Service Re-
quest) interrupt. Therefore, the SRQ Mask and bit 6 are discussed in the next
chapter where BASIC language controllers such as the -hp- Model 85 are discuss-
ed. Bit 6 is cleared when the condition for requesting service no longer exists.
Bit 5 will be true when an attempted calibration failed. The bit is cleared when IN-
STAT is executed.
Bit 4 is true when the 3468A front panel SRQ key is pressed. The bit is cleared
when INSTAT is executed.
Bit 3 is true when a hardware error is detected such as from the self test. It is
cleared when the Binary Status is read, see the B1 command code.
Bit 2 will be true when an invalid command is sent to the 3468A. It is cleared
when INSTAT is executed.
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