Hi Emma,
Here are some questions/suggestions:
- Can you send your startup script?
- How have you set the interpose interface, etc?
- Does your device use serial/RTU (binary) or serial/ASCII protocol?
- What is the slave address of your device?
- You have turned on asynTrace for the underlying asyn serial port.
Please also turn on asynTrace for the Modbus asyn port. That should be
very helpful.
Once I know how it is configured I can figure out if those 8 characters
it is sending are correct.
Mark
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of
[email protected]
Sent: Tuesday, November 24, 2009 10:52 AM
To: [email protected]
Subject: Modbus help
Hi,
I'm trying to get an RS-485 chain of N2300 temperature monitors talking
to EPICS using the asyn modbus support (R1-3) and so far am not having
much luck. Basically I just get no response back from any of them,
although I'm pretty confident I'm sending out the right message (I
checked it with a serial analyser) and have configured the correct comms
setting.
After iocInit I get the following message on the console (with asynTrace
turned on):
2009/11/24 16:03:34.302 drvModbusAsyn::doModbusIO port readTemp is
disconnected
and then lots of I/O errors:
02 03 00 01 00 01 d5 f9
2009/11/24 16:03:38.952 drvModbusAsyn::doModbusIO port readTemp error
calling writeRead, error=, nwrite=5/5, nread=0
2009/11/24 16:03:39.302 ME02P-DI-TMON-01:TEMP1 devAsynFloat64::process
read error
2009/11/24 16:03:40.452 drvModbusAsyn::doModbusIO port readTemp has I/O
error
2009/11/24 16:03:40.452 /ty/72/0 write 8
02 03 00 01 00 01 d5 f9
2009/11/24 16:03:41.952 drvModbusAsyn::doModbusIO port readTemp error
calling writeRead, error=, nwrite=5/5, nread=0
2009/11/24 16:03:43.452 drvModbusAsyn::doModbusIO port readTemp has I/O
error
2009/11/24 16:03:43.452 /ty/72/0 write 8
....... etc
asynReport prints the following:
modbus port: readTemp
asynOctet server: ty_72_0
modbusFunction: 3
modbusStartAddress: 01
modbusLength: 01
plcType: N2300
I/O errors: 119
Read OK: 0
Write OK: 0
pollDelay: 1.500000
Time for last I/O 0 msec
Max. I/O time: 0 msec
value = 0 = 0x0
Am I likely to be chasing a wiring/hardware issue here or is there
something standing out that indicates a problem higher up? This is the
first time I've tried to use modbus so I'm not sure what a 'working'
system looks like!
Thanks in advance,
Emma
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