R
Hi,
I'm wondering if anyone has dealt with the Modbus communications (RTU) package contained within the Emerson Micromotion Coriolis flow meters.
To give you a little background, I'm new to Modbus code. I've recently been tasked with learning how to use it to communicate with said flowmeters in labview.
I downloaded the modbus labview code (created by Maarten Van Bree) here (http://www.air.nl/nlibrary/modbus_vi.html)
I then tested with it with the Modbus Serial RTU Simulator by Conrad Braam (http://www.codeguru.com/network/mod_rssim.html)
and had great success learning how to create commands etc... I was able to write data to the simulator as well as read data from it.
Since then, I tried the same format with the Micromotion Sensor and I do get a response from it (ie, a correctly framed response with CRC) but the meat of the data contained is always zeros. For example a sample command request might be:
0203 9C66 0001 4A76
where
02 = Modbus Unit Address
03 = Read Function
9C66 = 40038 = Starting Register
0001 = # of registers to read from
4A76 = CRC
and the return string (Read Holding Registers) might look like:
0203 0200 00FC 44
where
02 = Modbus Unit Address
03 = Read Function
02 = byte Count
0000 = "Supposedly contains data"
FC44 = CRC
Everything looks great except the string of '0000'. I should be getting non-data here and for some reason i'm not....
If anyone has any suggestions as to why data isn't appearing, please contact me at [email protected]
Thanks,
Regis
I'm wondering if anyone has dealt with the Modbus communications (RTU) package contained within the Emerson Micromotion Coriolis flow meters.
To give you a little background, I'm new to Modbus code. I've recently been tasked with learning how to use it to communicate with said flowmeters in labview.
I downloaded the modbus labview code (created by Maarten Van Bree) here (http://www.air.nl/nlibrary/modbus_vi.html)
I then tested with it with the Modbus Serial RTU Simulator by Conrad Braam (http://www.codeguru.com/network/mod_rssim.html)
and had great success learning how to create commands etc... I was able to write data to the simulator as well as read data from it.
Since then, I tried the same format with the Micromotion Sensor and I do get a response from it (ie, a correctly framed response with CRC) but the meat of the data contained is always zeros. For example a sample command request might be:
0203 9C66 0001 4A76
where
02 = Modbus Unit Address
03 = Read Function
9C66 = 40038 = Starting Register
0001 = # of registers to read from
4A76 = CRC
and the return string (Read Holding Registers) might look like:
0203 0200 00FC 44
where
02 = Modbus Unit Address
03 = Read Function
02 = byte Count
0000 = "Supposedly contains data"
FC44 = CRC
Everything looks great except the string of '0000'. I should be getting non-data here and for some reason i'm not....
If anyone has any suggestions as to why data isn't appearing, please contact me at [email protected]
Thanks,
Regis