BK Precision VSP12010, Инструкция по эксплуатации

Страница: 43 / 68

The Status Byte Register
The status byte summary register reports conditions from other status
registers.Query data that is waiting in the instrument’s output buffer is immediately reported
through the “message available” bit (bit 4). Bits in the summary registers are not latched.
Clearing an event register will clear the corresponding bits in the status byte summary
register. Reading all messages in the output buffer, including any pending queries will clear
the message available bit.
BIT DEFINITIONS-STATUS BYTE REGISTER
BIT DESCRIPTION DECIMAL
VALUE DEFINITION
0
Not Used
1
Always set to 0.
1
Not Used
2
Always set to 0.
2
Questionable Data
4
One or more bits are set in the Questionable
Data register (bits must be “enabled” in enable
Register)
3
Not Used
8
Always set to 0.
4
Message Available
16
Data is available in the Instrument’s output
buffer.
5
Standard Event
32
One or more bits are Set in the Standard Event
register (bits must be “enabled” in enable regist).
6
Request Service
64
The Instrument is requesting the SERVICE
(Serial Poll).
7
Not Used
128
Always set to 0.
The Status byte summary register is cleared when:
♦
You execute a * CLS (clear status) command.
♦
Querying the standard event and questionable data registers will clear only the respective
bits in the summary register.
The status byte enable register (request service) is cleared when:
*
You turn on the power to the instrument.
* You execute a *SRE 0 command.
USING *STB? TO READ THE STATUS BYTE
The *STB? (Status byte query) command is similar to a serial poll except it is pro-
cessed like any other instrument command. The *STB? Command returns the same result
as an IEEE-488 serial poll except that the “request service” bit (bit 6) is not cleared if a serial
poll has occurred. The *STB? Command is not handled automatically by the IEEE-488 bus
interface hardware and the command will be executed only after previous commands have
completed. Polling is not possible using the *STB? Command. Using the *STB? Command
does not clear the status byte summary register.
41