Service Request Enable Register - Keithley 6517B Reference Manual

Model 6517B Electrometer Reference Manual
The IEEE-488.1 standard has a serial poll sequence that also reads the status byte register and is
better suited to detect a service request (SRQ). When using the serial poll, Bit B6 is called the RQS
bit. Serial polling causes Bit B6 (RQS) to reset. Serial polling is discussed in more detail later in this
section (see Serial Poll and SRQ).
Any of the following operations clear all bits of the status byte register:

Cycling power

Sending the *CLS common command
The MAV bit may or may not be cleared.

Service request enable register

This register is programmed by the user and serves as a mask for the status summary message bits
(B0, B2, B3, B4, B5 and B7) of the status byte register. When masked, a set summary bit in the
status byte register cannot set Bit B6 (MSS/RQS) of the status byte register. Conversely, when
unmasked, a set summary bit in the status byte register sets Bit B6.
A status summary message bit in the status byte register is masked when the corresponding bit in the
service request enable register is cleared (0). When the masked summary bit in the status byte
register sets, it is ANDed with the corresponding cleared bit in the service request enable register.
The logic "0" output of the AND gate is applied to the input of the OR gate and does not set the
MSS/RQS bit in the status byte register.
A status summary message bit in the status byte register is unmasked when the corresponding bit in
the service request enable register is set (1). When the unmasked summary bit in the status byte
register sets, it is ANDed with the corresponding set bit in the service request enable register. The
logic "1" output of the AND gate is applied to the input of the OR gate and thus, sets the MSS/RQS bit
in the status byte register.
The individual bits of the service request enable register can be set or cleared by using the following
common command (see
*SRE <NRf>
The service request enable register can be read using the following common query command (see
Common commands
*SRE?
The service request enable register is not cleared when it is read using the *SRE? query command.
The service request enable register clears when power is cycled or a parameter (n) value of zero is
sent with the *SRE command (*SRE 0).
6517B-901-01 Rev. C / August 2015
Common commands
(on page 12-1) for details):
(on page 12-1) for details):
Section 13: Status structure
13-13