Receive error -33156 with a [c]FP-20xx and a [c]FP-AIO-6xxHardware: Compact FieldPoint>>Analog I/O Modules>>cFP-AIO-600, Compact FieldPoint>>Analog I/O Modules>>cFP-AIO-610
Problem: I am running a LabVIEW 7.1 VI targeted to my cFP-2020. The VI acquires data from the AI channels on a cFP-AIO-610 on my cFP bank and/or writes current values to AO channels on the same module. Intermittently I receive error -33156. Why does this happen and what is the solution? Solution: When running an embedded application on a [c]FP-20xx controller with a [c]FP-AIO-600 or [c]FP-AIO-610 in the bank, if the application accesses the [c]FP-AIO-6xx (FP Read or FP Write) and is interrupted by a higher priority thread, the I/O module may reset itself causing error -33156. The module resets itself because it has a built in watchdog that ensures the module does not wait more than 50 ms for the semaphore. For most FieldPoint analog I/O modules, except for the cFP-AI-118, there is a semaphore that ensures the controller and the I/O module don't access the shared memory on the I/O module simultaneously. If the [c]FP-AIO-6xx waits for more than 50 ms for the semaphore it reboots itself. The I/O module is not granted the semaphore because the controller was preempted by the higher priority thread after acquiring the semaphore to do the read or write. Applications that generally experience this situation are those that have a higher priority loop (higher than normal) with a very CPU intensive process and a very small wait. They also have a normal priority thread that is doing the I/O module reads and writes. The solution to this is to ensure that your RT application has sufficient waits in VIs with greater than normal priority, so that other normal priority threads have time to execute. Some applications requirements are too intensive for the processing power of the [c]FP-20xx family and it may be beneficial to use a cFP-21xx family controller with about four times the processing power. Related Links: cFP 2120 Controller webpage Attachments:
Report Date: 05/01/2005 Last Updated: 05/02/2005 Document ID: 3L0HGEVE |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
