22
SCIP Command Operation
6.4.2 *OPC?
Syntax
*OPC?
Description
This query returns an ASCII character “1” when all pending operations have
been finished.
Result
ASCII character “1”.
Possible error codes
4
Example 1
*OPC?
Result
“1”
Example 2
:SWIT1 4; SWIT2 4; *OPC?
Result
“0”
Timing
In Example 2 the Mini-Matrix did not have the time to execute the
command. Hence a “0” is returned. A subsequent *OPC? will return a “1” as
shown in Example 1.
The timing to execute a command depends on the length of the command
(in case of concatenated commands). In case of switching commands like
on Example 2, the controller will first command each switch to set its new
position, then query each switch to ensure that the positions are closed and
finally respond with a “1” to the
*OPC?
query.
As a rule of thumb electromechanical switches require approximately 10-
15ms to switch position. But the
*OPC?
query will return a “1” only after the
switches have not only changed its positions, but rather also confirmed its
position. So it is safe to consider some safety margin and expect a
response of “1” after about 50ms per switch. As an example, if 2 switches
are commanded wait about 100ms before issuing an
*OPC?
query that will
return a “1”.