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<== Date ==> <== Thread ==>
Subject: pv invalid using stream
From: 网易邮件中心 via Tech-talk <tech-talk at aps.anl.gov>
To: tech-talk at aps.anl.gov
Date: Mon, 9 May 2022 16:46:02 +0800 (CST)
Hi all,
     I have a python program( xxx.py ), which simulate a hardware( actually it was prepared for a can bus device ). The xxx.py uses TCP protocols.
     The xxx.py would produce data, I intend to do the comunication with PC-linux and epics using xxx.py. 
     I means ask IOC get the value produced by xxx.py.

the xxx.py send and receive message like these:

sending msg: b'\x05\x03\x01\x04A\x00\x00\x00W\x19'
receiving msg: b'\x05\x03\x02\x04@\xe0\x00\x00W '       # 7 byte?
sending msg: b'\x05\x03\x02\x04A\x10\x00\x00V\xef'
receiving msg: b'\x05\x03\x01\x04A\x00\x00\x00W\x19'   # 8 byte?
sending msg: b'\x05\x03\x01\x04A \x00\x00V\xd3'
receiving msg: b'\x05\x03\x02\x04A\x10\x00\x00V\xef'
sending msg: b'\x05\x03\x02\x04?\x80\x00\x00N\xea'
receiving msg: b'\x05\x03\x01\x04A \x00\x00V\xd3'
sending msg: b'\x05\x03\x01\x04@\x00\x00\x00V\xe5'
receiving msg: b'\x05\x03\x02\x04?\x80\x00\x00N\xea'
sending msg: b'\x05\x03\x02\x04@@\x00\x00W\x02'
receiving msg: b'\x05\x03\x01\x04@\x00\x00\x00V\xe5'   # has some strange character?
sending msg: b'\x05\x03\x01\x04@\x80\x00\x00W\r'
receiving msg: b'\x05\x03\x02\x04@@\x00\x00W\x02'
sending msg: b'\x05\x03\x02\x04@\xa0\x00\x00V\xf4'
receiving msg: b'\x05\x03\x01\x04@\x80\x00\x00W\r'
sending msg: b'\x05\x03\x01\x04@\xc0\x00\x00V\xd9'
receiving msg: b'\x05\x03\x02\x04@\xa0\x00\x00V\xf4'


Question:
I created an example ioc, added the db and proto, added " drvAsynIPPortConfigure("PS1","127.0.0.1:9011") " and STREAM_PROTOCOL_PATH in st.cmd.
--db file:
record(ai, "temperature")
{
 field(DESC, "temperature in tank")
 field(DTYP, "stream")
 field(INP, "@HSPY.proto GetTem PS1")
 field(EGU, "degree")
 field(SCAN, "1 second")
}
--proto file:
Terminator = LF;
GetTem {
        in "%*2r%r%*4r";
        ExtraInput = Ignore;
}

Then I got in IOC:
---epics> dbpr temperature
ASG:                DESC: temperature in tank               DISA: 0
DISP: 0             DISV: 1             NAME: temperature   RVAL: 0
SEVR: INVALID       STAT: UDF           SVAL: 0             TPRO: 0
VAL: 0

---epics> dbtr temperature
record active

Question：
1) Another better tool than stream device?
2) Does the proto I the right?
3) why my temperatre pv was invalid undefined? 
     4) the received message was not so regular, stream device suitable?
Could someone do me a favor. ioc was run in unbuntu PC, epics was 7.0.x.

Thanks,
Liang


 
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