Re: asyn w/serial device pushing data

[Eric Norum <eric@norum.ca>]

The example shown is for a device that produces a message on request.

In your case the device sends unsolicited messages so your plan to invoke readIt rather than writeRead is correct.   You would then not need the epicsThreadSleep -- just make sure that the timeout specified in the readIt invocation is longer than the expected time between hardware triggers.  
If you've interposed the EOS processing module the readIt routine will not return until timeout or receipt of the end-of-string character.

On Apr 2, 2012, at 12:16 PM, Fong, Nia W. wrote:

> Hi,
> 
> I'd like to use asynPortDriver to connect to a serial device that pushes data when triggered by a hardware pulse.
> 
> If I use SCAN=I/O Intr and the pollThread() example code below from a previous tech-talk thread will my record be triggered to read every time there is new data?  Does this code mean my driver is constantly polling the serial port at a POLL_DELAY?
> 
> I only need to read, so can I call pasynOctetSyncIO->readIt() instead?  
> 
> How will I know that the serial device has finished pushing it's data for that trigger?  Does asyn/pasynOctetSynIO->readIt() wait for the OutputEos in the serial buffer before returning the received message?  Or is asyn waiting to read sizeof(receiveMessage) characters?
> 
> 
>> void myPortDriver::pollThread()
>> {
>>    while(1) {
>>          status = pasynOctetSyncIO->writeRead(pasynUserHMS, sendMessage, numSend, 
>>                                         receiveMessage, sizeof(receiveMessage), 
>>                                         WRITE_READ_TIMEOUT, &numSent, responseLen, &eomReason);
>>          sscanf(receiveMessage, "TEMP=%f,CURRENT=%f", &temperature, &current);
>>          setDoubleParam(temperatureParam, temperature);
>>          setDoubleParam(currentParam, current);
>>          callParamCallbacks();
>>          epicsThreadSleep(POLL_DELAY);
>>    }
>> }
>> 
> 
> 
> Thank you in advance for any suggestions or comments.
> 
> Nia 

-- 
Eric Norum
eric@norum.ca