There is something wrong, because the record should only be processing when the ring buffer has something in it. Once you understand the choices that Asyn has made though, writing the software is actually simpler than it would be without asyn. First, you will need to write the code for a basic device support layer. Email me about changes to this bug report. You need to log in to change this bug’s status.
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How To Write Device Support that uses Asyn Driver
The asyn device support callback function puts each value in a ring buffer and calls scanIoRequest each time.
Connecting If we want to talk to a real world device that already has an asyn Port registered, we have to connect to it by name: Accept Reject Read More.
Note that this code does not take a lock around the call to epicsRingBytesPut, because that is not supposed to be required according to the Application Developer’s Porrt. Andrew Johnson anj wrote on Some of these fields we are allowed or even expected to set, whereas others should not be touched.
Bug # (mantis) “scanIoRequest is sometimes not process” : Bugs : EPICS Base
System configuration 3 systems were tested. Our code needs to pull in some headers first: See full activity log.
The asynPrint call in this function was added since asyn R to help in debugging, but otherwise the code is that from asyn R The asynDriver Documentation describes the fields inside the asynDriver structure. Writing epucs that calls Asyn is confusing until you understand the approach it expects you to use.
To post a comment you must log in. When the record processes for example longin record it calls the following function in devAsynInt What is an asynUser? Email me about changes to this bug report.
Because device support thinks the ring buffer is empty it queues a call to the driver and sets PACT this is asynchronous device support. If we want to talk to a real world device that already has an asyn Port epis, we have to connect to it by name:.
Getting Started First, you will need to write the code for a basic device support layer. Comment on this change optional. There are 2 reasons I can think of why the records would not process when scanIoRequest is called.
When running on the problematic Linux system I do see very rare less than 0. It is a 4-processor system. Once you understand the choices that Asyn has made though, writing the software is actually simpler than it would be without asyn.
How To Write Device Support that uses Asyn Driver – EPICS Controls
We’ll assume you’re ok with this, but you can opt-out if you wish. Other bug subscribers Subscribe someone else. On several tested systems this works fine, and the record processes exactly as many times as the callback is called, i.
There are other records, the frame counters for example, that never appear in the printf calls in dbProcess or device support, but which are ending up with extra ring buffer values when the driver is done with its burst of activity. Problem was a reordering of instructions by newer, more aggressive, GCC optimizers. This is the code for getCallbackValue: You are not directly subscribed to this bug’s notifications.
Initially you will probably create an asynUser for each record, since at least in theory the user could create a database that processes all your records at once. There are very good reasons behind the design of Asyn which is epivs to simplify the work involved in writing robust, portable code, but this does result in the need to learn the Asyn approach.
Bug reported by rivers on epiics