Omron E5CN via Modbus

[Ano Ano]

Hello,

I have a Omron E5CN Temperature controller that I want to use with Labview and Modbus.

I am able to communicate with this controller using Omron's Thermomini software.

MAX is able to validate the and open a session with the device. The controller is connected via a RS232 to USB converter.

I set the controller to modbus but no luck. Maybe its because I dont know how to use the modbus drivers, I havent attempted to use such a device with Labview so I am lost with all this machine codes !

Any advice towards a newbie on how to use this controller with Labview/Modbus?

The programming manual for this controller is here

[Tim_S]

The hardest thing to find is the base Modbus address. No manufacturer seems to put the exact correct address in their manuals, so you'll have to hunt a bit to find the correct base address. Everything after that is offset from the base address.

[JamesMc86]

Which mod us library are you using? Is it the free one off ni.com?

From a quick look at the commands you need to be using the register accesses for the data. With the free mod us library I believe you should then be able to send the addresses as the manual suggests, some other implementations require an offset depending on the data you are reading. Generally 3 for read only registers (or variables as the manual calls thru) or 4 for read/write registers so the address for a read only register at address 1 appears as 40001. the addresses appear to be detailed in section 6.

Hopefully this is a starting point to decipher some of the data you are seeing. Let me know what library your using and I may. E able to be a little more specific.

[ShaunR]

I would start with the "echo" command. Once you get that working (i.e. eliminate all the serial configurations and get something tangible back); it should be plain sailing from there.

[Neville D]

There seems to be a bug in the Modbus CRC calculation vi in the NI library. Replace it with the attached VI that I got from Steve Brooks on the NI website.

MBcrc.vi

[Ano Ano]

This file is written with Labview v11, can you please down-convert it to v10.1?

[asbo]

Backsaved to LabVIEW 8.0.

MBcrc.LV80.vi

There seems to be a bug in the Modbus CRC calculation vi in the NI library. Replace it with the attached VI that I got from Steve Brooks on the NI website.

Do you know what the changes were in this VI?

[Neville D]

Sorry, just saw this. I don't remember now, but I checked the CRC generation code and the NI version didn't exactly conform to the ModBUS spec document (Pg 14 & Pg 39):

http://www.modbus.org/docs/Modbus_over_serial_line_V1_02.pdf

Bottom line was: Steve Brooks' version worked with a ModBUS device I was using, and the NI version didn't.

[Xuan-Thai Nguyen]

Hi every one,

I can connect and run E5CN tempt. controller to Labview through Modbus.

Attached files are  my  programming test for E5CN. 

 

E5CN_test new.vi MBcrc (2).vi String Hex to Interger Decimal.vi

[Porter]

I would highly recommend that you use one of the existing modbus libraries to communicate with the E5CN.

See:

 

OR:
https://github.com/NISystemsEngineering/LabVIEW-Modbus-API

 

[Xuan-Thai Nguyen]

Dear Poster,

Thank you for your recommendation.

How do I install Labview modbus API?

[Porter]

Its easiest to use VI Package manager. Just search for Modbus, select the package and install.