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*SRE
Meaning and Type
Service Request Enable
Description
This command sets the condition of the Service Request Enable Register. This register determines which bits from the
Status Byte Register (see *STB for its bit configuration) are allowed to set the Master Status Summary (MSS) bit and the
Request for Service (RQS) summary bit. A 1 in any Service Request Enable Register bit position enables the corresponding
Status Byte Register bit and all such enabled bits then are logically ORed to cause Bit 6 of the Status Byte Register to be set.
See "Chapter 8 - Status Reporting" for more details concerning this process.
When the controller conducts a serial poll in response to SRQ, the RQS bit is cleared, but the MSS bit is not. When *SRE
is cleared (by programming it with 0), the power supply cannot generate an SRQ to the controller.
Returned Parameters
Related Commands
If *PSC is programmed to 0, then the *SRE command causes a write cycle to nonvolatile memory.
The nonvolatile memory has a finite number of write cycles (see Table A-2, Supplementary
Characteristics). Programs that repeatedly write to nonvolatile memory can eventually exceed the
maximum number of write cycles and may cause the memory to fail.
*STB?
Meaning and Type
Status Byte
Device Status
Description
This query reads the Status Byte register, which contains the status summary bits and the Output Queue MAV bit. Reading
the Status Byte register does not clear it. The input summary bits are cleared when the appropriate event registers are read
(see "Chapter 8 - Status Reporting" for more information). The MAV bit is cleared at power on or by *CLS.
A serial poll also returns the value of the Status Byte register, except that bit 6 returns. Request for Service (RQS) instead
of Master Status Summary (MSS). A serial poll clears RQS, but not MSS. When MSS is set, it indicates that the power
supply has one or more reasons for requesting service.
Bit Position
7
OPER
Condition
Bit Weight
128
ESB = Event status byte summary; MAV = Message available.
MSS = Master status summary; OPER = Operation status summary.
QUES = Questionable status summary; RQS = Request for service.
70
Language Dictionary
Device Interface
Command Syntax
Parameters
Default Value
Example
Query Syntax
Bit Configuration of Status Byte Register
6
5
1
ESB
MSS
(RQS)
64
32
1
Also represents RQS.
*SRE <NRf>
0-to 255
(See *PSC)
*SRE 20
*SRE?
<NR1>
(Register binary value)
*ESE
*ESR
*PSC
4
3
MAV
QUES
16
8
2
These bits are always zero.
2
1
0
2
2
2
4
2
1
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