M - service request mask…… 62, M - service request mask – Measurement Computing Digital488/80A User Manual
Page 68
M - Service Request Mask
SYNTAX
Mmask
Define the Service Request (
SRQ
) conditions, where
00
≤
mask
≤
31
, as summed
from the following states:
•
0
- (Default)
SRQ
is disabled.
•
1
-
SRQ
on Service input transition.
•
2
-
SRQ
on EDR input transition.
•
4
-
SRQ
on IEEE 488 bus error.
•
16
-
SRQ
on Ready.
Note:
The Service Request Mask commands are
OR
ed together as received. To delete
any one command, it is necessary to program the default mode
M0
, then
reprogram the desired commands.
DESCRIPTION
The Service Request Mask (
M
) command is used by the Digital488/80A to alert the controller to one of several
conditions described below. Multiple Service Request (
SRQ
) conditions can be enabled simultaneously by issuing
them separately or by combining them in one command string. If multiple Service Request Mask commands are
contained within the same command string, each command must be followed by an Execute (
X
) command. An
alternative is to add up the values of each Service Request Mask command desired, and send a single command with
the sum of the desired commands. The Service Request Mask commands are
OR
ed together as received. To delete
any one command, it is necessary to program the default mode
M0
, then reprogram the desired commands. 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
).
Default mode
M0
disables the
SRQ
function, preventing the Digital488/80A from generating a Service Request.
Mode
M1
enables the Digital488/80A to generate a Service Request when the Service input line makes a transition.
Refer to the Invert (
I
) command for programming the polarity of the Service input line.
Mode
M2
enables the Digital488/80A to generate a Service Request when the EDR input makes a transition. Refer to
the Invert (
I
) command for programming the polarity of the EDR input line.
Mode
M4
enables the Digital488/80A to generate a Service Request when a bus error occurs. The most common bus
error is sending an invalid command to the Digital488/80A. For example, when mode
M4
is selected, selecting Data
Format
F6
(which does not exist) causes the Digital488/80A to generate a Service Request.
Mode
M16
enables the Digital488/80A to generate a Service Request when it has completed the execution of a set of
commands from the bus controller. This may be used by the controller to assure the completion of a set of commands
before sending a subsequent set of commands.
EXAMPLE 1: Invalid Command.
PRINT#1,"CLEAR08"
Line 1: Reset the Digital488/80A.
PRINT#1,"OUTPUT08;M4X"
Line 2: Select SRQ on bus error.
PRINT#1,"OUTPUT08;W7X"
Line 3: Send an invalid command (no
W
command exists).
Note: ERROR and SRQ LED indicators should illuminate.
EXAMPLE 2: Alternative command strings.
PRINT#1,"CLEAR08"
Line 1: Reset the Digital488/80A.
PRINT#1,"OUTPUT08;M1X M4X"
Line 2: Select SRQ on bus error, and SRQ on Service input transition.
PRINT#1,"OUTPUT08;M5X"
Line 3: This command string would have the same effect as the command
string sent in the line above where
M1X
plus
M4X
equals
M5X
.
62 Digital488/80A Commands
967695
Digital488/80A User's Manual