Re: streamDevice configuration issues with serial ports

[Mark Rivers via Tech-talk <tech-talk at aps.anl.gov>]

I agree with Michael, the Modbus driver may be better, especially if there are multiple registers to read.

If you want to use streamDevice instead then here are some of the things you are doing wrong.

- Modbus RTU does not use terminators, so you need to remove those from you protocol file.

- Your command needs to end with the correct CRC. streamDevice can compute that, or you can hardcode it if your command is always the same.

- You cannot read the response with a simple %r because the first few bytes of the response contain the device address, the function code, and the response length. The actual data comes after those. 

Mark

Sent from my iPhone

> On Oct 28, 2024, at 11:04 PM, Michael Davidsaver via Tech-talk <tech-talk at aps.anl.gov> wrote:
> 
> On 10/28/24 18:26, LONG FENG via Tech-talk wrote:
>> Hi all,
>> I have a sensor that communicates via RS485 with the Modbus RTU protocol. I want to use streamDevice
> 
> I would recommend investigating the dedicated modbus driver.
> 
> https://urldefense.us/v3/__https://github.com/epics-modules/modbus__;!!G_uCfscf7eWS!c4aIWok1tNUpdvoK687_GbGUCAbx6C1QeCs-S8lpaB_ezoWQZwEjMofav56BrZ-IOIyZ5jrM53AfDHb1aGIp4Bo3OQ$
> 
>> to read the sensor values, but I've found that there is no data transmission between the system and the sensor, and the following issues have occurred：
>> /epics> 2024/10/28 21:00:05.370941 SI Sensor:Data: No reply within 10000 ms to "<01><04><00><00><00><06>p<08><0d><0a>"
>> 2024/10/28 21:00:20.484243 SI Sensor:Data: No reply within 10000 ms to "<01><04><00><00><00><06>p<08><0d><0a>"
>> 2024/10/28 21:00:35.322913 SI Sensor:Data: No reply within 10000 ms to "<01><04><00><00><00><06>p<08><0d><0a>"
>> 2024/10/28 21:00:50.427348 SI Sensor:Data: No reply within 10000 ms to "<01><04><00><00><00><06>p<08><0d><0a>"
>> /
>>     My protocol(RS485Test.proto) file is written like this：
>> /
>> /
>> /Terminator = CR LF;
>> InTerminator = CR LF;
>> ReplyTimeout = 10000;
>> ReadTimeout = 10000;
>> getData
>> {
>>   out "\x01\x04\x00\x00\x00\x06\x70\x08";
>>   in "%r";
>> }
>> /
>>     Record(RS485Test.db)：
>> /record(ai, "Sensor:Data")
>> {
>>     field(DTYP, "stream")
>>     field(INP, "@RS485Test.proto getData SI")
>>     field(SCAN, "5 second")
>> }
>> /
>> /
>> /
>>     IOC st.cmd:
>> /
>> /
>> /#!../../bin/linux-x86_64/dataProcessing
>> < envPaths/
>> /
>> dbLoadDatabase("../../dbd/dataProcessing.dbd",0,0)
>> dataProcessing_registerRecordDeviceDriver pdbbase
>> epicsEnvSet ("STREAM_PROTOCOL_PATH", "/home/training/examples/dataProcessingApp/Db")
>> drvAsynSerialPortConfigure("SI", "/dev/ttyS3")
>> asynSetOption("SI", 0, "baud", "9600")
>> asynSetOption("SI", 0, "bits", "8")
>> asynSetOption("SI", 0, "parity", "none")
>> asynSetOption("SI", 0, "stop", "1")
>> asynSetOption("SI", 0, "clocal", "Y")
>> asynSetOption("SI", 0, "crtscts", "N")
>> ## Load record instances
>> dbLoadRecords("../../db/RS485Test.db")
>> iocInit()/
>>     Is there anything wrong with these?
>