Measurement Computing Digital488 - Manual (Page 52)

Section 3 Command Descriptions
3.22
Service Request Mask (SRQ) Mn
The Service Request (SRQ) mode is used by the Digital488 to alert the
controller to one of several conditions described below. Multiple SRQ conditions can
be enabled simultaneously by issuing them sepatately or by combining them in one
command. If multiple SRQ commands are contained within the same command string,
each SRQ command should be followed by an Execute command (X). The
programmed SRQ modes will remain enabled until the M0 command is sent, or the
controller sends a Device Clear (DCL), Selected Device Clear (SDC), or Interface Clear
(IFC) command.
M0 SRQ is disabled
M1 SRQ on Service input transition
M2 SRQ on EDR input transition
M4 SRQ on bus error
M8 SRQ on Self-Test error
M16 SRQ on Ready
MO default mode disables the SRQ function, preventing the Digital488 from
generating a Service Request.
M1 will generate a Service Request when the Service Input line makes a
transition. Refer to the Invert command (I64) description for programming the polarity
of the Service input line.
M2 will generate a Service Request when the EDR input makes a transition.
Refer to the Invert command (I32) description for programming the polarity of the
EDR input line.
M4 will generate a Service Request when a bus error occurs. The most
common bus error is sending an invalid command to the Digital488. For example,
attempting to select an 'F6' format when no 'F6' format exists will generate a Service
Request when the M4 mode is selected.