MTS Series 793 Application - Manual (Page 212)

MTS MultiPurpose TestWare®
External Command Process
Command Processes 212
About Starting External Commands
If the external command is not running when MPT starts the External Command
process, your test will stop responding.
To ensure that your external program is running when it is needed, do one of the
following:
• Start your external program source before you start your MPT procedure.
This ensures that the external command is running when the External
Command process starts and limits unwanted bumps in your command
signal.
• If your external programmer supports digital input and output signals,
configure a Digital Output to start the external program, and a Digital Input
Detector Process to start the External Command process.
Considerations for
using the External
Command process
Using the External Command process can result in unexpected actuator
movement.
Unexpected actuator movement may injure personnel and damage
equipment.
Consider the possibility of unexpected actuator movement when designing or
executing a test that includes an External Command process.
The External Command process, when used in combination with a specific type
of control mode and MPT option, may cause the system to “bump” (perform an
immediate step adjustment) when triggered. This occurs as the system reacts to
the offset component of the program in the External Command process.
Specifically, this may occur when the External Command process is used in a
station that uses one of the following control modes:
• A Dual Compensation control mode in which the Compensation Type is
Amplitude Control Only,
• A Cascaded PIDF control mode in which the Cascade Type is Amplitude
Control Only,
WARNING