Performance Motion Devices PR8358120, Руководство пользователя

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Operation
Prodigy/CME PC/104 User’s Guide
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that should be observed during run time operation of downloaded C-Motion code. The table above provides these
numerical limits.
For user downloaded code that does not correctly observe these limits, or for files that have become corrupted, there
are a number of fault conditions that can occur while the C-Motion Engine is executing downloaded user application
code. These very serious run-time faults include instruction errors - indicating that an unknown instruction was
encountered during execution of the user’s code, and address faults - indicating that either a program space or RAM
space access limit was violated. If either of these conditions occur, the C-Motion Engine will immediately halt user
code execution, and reset the Prodigy/CME PC/104 card. This C-Motion Engine-initiated reset is identical to the
reset that occurs after sending a PRP
Reset action, except that the cause of the reset is recorded as ‘C-Motion Engine
user code Fault’ rather than ‘commanded’ reset. See Section 2.6.2, “Reset,” on page 50 for more information on the
Reset command. See Section 2.3.6, “Reset Monitor,” on page 39 for information on retrieving the reset cause.
Whether or not user application code is running, after reset or power up, the C-Motion Engine begins processing PRP
actions sent to it. These commands are typically sent from a host controller. The supported commands include
functions such as checking the downloaded user application code version stored in the C-Motion Engine, and sending
and receiving messages to the user code loaded onto the C-Motion Engine.
For additional guidelines on managing run-time usage of the C-Motion Engine see the C-Motion Development Tools
Manual .
2.4.3 Task Control
The primary purpose of the C-Motion Engine is to execute user application code that has been downloaded to it using
the C-Motion Engine development system.
In a production environment, this code will typically automatically start upon power up, and run continuously while
the system is in operation. For debugging however, there are a number of additional controls.
At any point in time it is possible to stop or restart execution of the C-Motion Engine user application code. To access
this function the PRP action
Command is sent to the CMotionEngine resource.
Whether or not the user application code automatically executes upon powerup or reset can also be controlled. The
two options are operation under manual mode, in which case the user’s code will not begin execution until an explicit
start command is given, and auto-start, where the code automatically begins execution from power up or reset. The
PRP action
Set sent to the CMotionEngine resource allows setting of the user code start mode.
In addition to these functions, it is also possible to determine whether the user application code is presently running
or not. This status information may be useful during code debugging, or to help diagnose problems. This capability is
accessed via a
Get action sent to the CMotionEngine resource.
For a detailed description of the supported Prodigy/CME commands see the Prodigy/CME Programmer’s Reference .
2.4.4 Sending Messages to/from User Application
Code
A common function of user application code running on the C-Motion Engine is to parse command messages sent
to it by a host controller. For example a user might write code for the C-Motion Engine that responds to an “Extend
Extreme caution should be applied when stopping or starting user application code running on the C-Motion En-
gine, as depending on the specific application code, this may cause unexpected or unsafe motion. It is the respon-
sibility of the user to determine whether stopping or restarting of user application code is safe and appropriate.