Measurement Computing Serial488/4 - Manual (Page 51)

Section 3 Command Descriptions
3.12
Service Request (SRQ) Mn
The Service Request (SRQ) mode is used by the Serial488/4 to alert the
controller to one of several conditions described below . Multiple SRQ conditions can
be enabled simultaneously by issuing them separately or by combining them in one
command. If multiple SRQ commands are contained w ithin the same command
string, each SRQ command should be follow ed by an E xecute command ( X). The
programmed SRQ modes will remain enabled until the M0 command is sent, or the
controller sends a Device Clear (DCL) or Selected Device Clear (SDC). The factory
default setting as set by the Save Configuration command (
S0
) is M0, SRQ i s
disabled.
M0
SRQ is disabled
M1
SRQ on receipt of data on serial port 1
M2
SRQ on receipt of data on serial port 2
M4
SRQ on receipt of data on serial port 3
M8
SRQ on receipt of data on serial port 4
M16
SRQ on Ready
M32
SRQ on Error condition
M128
SRQ on Memory low condition
M?
Returns current SRQ mask
MO
default mode disables the SRQ function, preventing the Serial488/4 from
generating a Service Request.
M1
, M2, M4 and M8 will generate a Service Request when the data is received on
serial ports 1, 2, 3, and 4 respectively.
M16
will generate a Service Request w hen the Serial488/4 has completed the
execution of a set of commands from the bus controller. This is used by the controller
to assure the completion of a set of commands before
sending a subsequent set of
commands.
M32
will generate a Service Request w hen an error occurs. The most common
bus error is sending an invalid command to the Serial488/4. For example, attempting
to select an ' B15' baud rate w hen no ' B15' baud rate exists w ill generate a Service
Request when the M32 mode is selected.