Measurement Computing Digital232 - Manual (Page 37)

Section 3 Command Descriptions
3.15
Service Request (SRQ) Mn
The Service Request (SRQ) mode is used by the Digital232 to alert the host
computer to one of several conditions described below. When a service request
condition occurs, the string “SRQ n” will automatically be sent to the host computer,
where “n” is a number from 1 through 7. The number “n” is determined by the
conditions which have caused the service request, and is the sum of M1, M2, and M4.
Multiple SRQ conditions can be enabled simultaneously. If multiple SRQ
commands are contained within the same command string, each SRQ command
should be followed by an Execute command (X). An alternative is to add the values
of each SRQ command desired, and send one command with the sum of the desired
commands. The SRQ commands are ORed together as received. The programmed
SRQ modes will remain enabled until the M0 command is sent, or a Reset (@)
command is received.
M0 default mode disables the SRQ function, preventing the Digital232 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 programming error occurs. For
example, attempting to select an ‘F6’ format when no ‘F6’ format exists
will generate a Service Request when the M4 mode is selected.
Example:
@ reset the Digital232
M4 select SRQ on error
F7 send an invalid command.
ERROR LED should illuminate and “SRQ” is sent to the host