Model 8642A/B
Operation
STATUS BYTE
Overview The 8642A/B Status Byte consists of one
8-bit
byte which reflects Signal Generator
status.
All 8 status bits are updated whether the Signal Generator is in local or remote
mode.
Reading the
Status Byte
Clearing the
Status Byte
Each bit of the Status Byte monitors a particular aspect of the Signal Generator's
operation. Table 3-7, HP-IB Status Byte Bit Definitions (on the following page), details
the operating conditions which are monitored by the 8642 Status Byte.
The Status Byte can either be used to cause a Service Request or simply be read to monitor
the Signal Generator's operating status.
To read the Signal Generator's Status Byte, the controller must send the Serial Poll Enable
bus command and address the Signal Generator to talk. For example:
Program Statement (in BASIC)
10 S = SPOLL(719)
If the RQS bit is not set, the Status Byte will reflect the current status of the instrument.
If the RQS bit is set, the Status Byte will reflect the status of the instrument when the
RQS bit was first set (or when the Status Byte was last read with RQS set). To actually get
the current status of the instrument, the Status Byte should be read again. Note that the
act of reading the Status Byte (alone) does not clear any status bits.
If the instrument does not have an unresolved hardware error, the Status Byte will be
"cleared" by executing any of the following:
Sending Clear Status (CS).
Sending Instrument Preset (IP).
Sending Device Clear or Selected Device Clear.
Switching the Power from Standby to On.
You can also clear the Status Byte by clearing the individual status bits. Refer to Table
3-7 on the following page.
NOTE
Bits 3 (Local/Remote) and 4 (Ready) are not affected by "clearing" the
Status Byte. They always output their actual values.
3-29
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