HP E4418B Programming Manual page 104

Power Meter Remote Operation
Status Reporting
The Status Byte
The status byte summary register reports conditions from other status
registers. Query data waiting in the power meter's output buffer is
immediately reported through the "message available" bit (bit 4). Clearing
an event register clears the corresponding bits in the status byte summary
register. Reading all messages in the output buffer, including any pending
queries, clears the message available bit.
Table 1-5: Bit Definitions - Status Byte Register
Bit Decimal
Number Weight
0 1
1 2
2 4
3 8
4 16
5 32
6 64
7 128
1-80
Definition
Not Used (Always set to 0)
Device Status Register summary bit.
One or more bits are set in the Device Status
Register (bits must be "enabled" in enable register)
Error/Event Queue
Questionable Status Register summary bit.
One or more bits are set in the Questionable Status
Register (bits must be "enabled" in enable register).
Message Available
Data is available in the power meter's output buffer.
Standard Event
One or more bits are set in the Standard Event
register (bits must be "enabled" in enable register).
Request Service
The power meter is requesting service (serial poll).
Operation Status Register summary bit.
One or more bits are set in the Operation Status
Register (bits must be "enabled" in enable register).
HP E4418B/E4419B Programming Guide