Re: Help beginner with ASYN device support, ai record conversion to EGU

[Eric Norum <eric@norum.ca>]

1) LINR should be SLOPE.
2) I recommend that you have a look at StreamDevice -- it's now what I'd recommend as the best place to start to support a message-based device.


On May 13, 2013, at 10:07 AM, "Gomella, Andrew (NIH/NHLBI) [F]" <andrew.gomella@nih.gov> wrote:

> Hi,
> 
> I have been following Eric Norum's "How To Do Serial" guide ( http://www.aps.anl.gov/epics/modules/soft/asyn/R4-21/HowToDoSerial/tutorial.pdf) to write an application to control a serial port controller table top x-ray source.
> 
> So far everything works near perfectly (Thanks to Eric for the guide, and the writers of ASYN/EPICS), my only issue is that I am having trouble getting the Analog Input and Output fields to work properly. I can easily read and write the raw values (0 to 4095 due to it being a 12 bit DAC inside the xray's controller) but when I change the .db record to try and use ASYN's built in functions to convert the value I run in to issues. I'm definitely missing something that is probably obvious for most techtalk readers.
> 
> Here is one of the commands in the app source file.
> 
> {&DSET_AI, GPIBREAD, IB_Q_LOW, "RD1", NULL, 0, 127, NULL, 0, 0, NULL, NULL, NULL},
> 
> The controller responds to RD1 with 0000\r  with 0000 being from 0000 to 4095. (I tried using the format function, i.e. with "%u\r" but this didn't seem to work, but with NULL it does.)
> 
> Here is the corresponding section of my db file.  (which is how I was hoping it would work at first) srxr is the name of my device.
> 
> record(ai, "$(P)$(R):uAStatus")
> {
>    field(DESC, "Read Xray uA Monitor")
>    field(SCAN, "1 second")
>    field(DTYP, "srxr")
>    field(LINR, "LINEAR")
>    field(ASLO, "0.244")
>    field(AOFF, "0")
>    field(EGUF, "900")
>    field(EGUL, "0")
>    field(EGU, "uA")
>    field(INP,  "#L$(L) A$(A) @11")
> }
> 
> I tried changing DTYP to asynInt32, and then changing INP to the @asyn format, but this did not seem to work.
> 
> I also tried to change several of the fields, such as LINR to SLOPE. So far I only get the field showing as 0 (when it should be reading
> an output, or as the raw value.
> 
> Here are relevant portions of st.cmd
> 
> ## Register all support components
> dbLoadDatabase "dbd/srxr.dbd"
> srxr_registerRecordDeviceDriver pdbbase
> 
> ## Load record instances
> dbLoadRecords("db/devsrxr.db","P=srxr,R=,L=0,A=0")
> 
> drvAsynSerialPortConfigure("L0","/dev/ttyS0",0,0,0)
> asynSetOption("L0", -1, "baud", "9600")
> asynSetOption("L0", -1, "bits", "8")
> asynSetOption("L0", -1, "parity", "none")
> asynSetOption("L0", -1, "stop", "1")
> asynSetOption("L0", -1, "clocal", "Y")
> asynSetOption("L0", -1, "crtscts", "N")
> 
> As is, this just reads out the raw values of uA, rather than it being converted to EGU.
> 
> Alternatively someone can point me to example source code that runs a serial device, but is more complex
> than the filter wheel in the "How To Do Serial" guide (uses more record types like ai etc).
> 
> I couldn't find any that helped me with this issue.
> 
> Thanks,
> Andrew
> 

-- 
Eric Norum
eric@norum.ca