Watlow PM with Modbus TCP

Hi community,
I have a watlow pm temperature controller connected to my computer with an ethernet cable. I need to communicate with the device via modbus tcp. I know for sure that the unit is functioning as if I use a modbustcp test program (see the first attachement), then I can read the temperature of the K type thermocouple which is connected to the unit. (the IP is 192.168.10.3, and I read two words from address 360). The temperature on the screenshot is 23.61992C
I would like to do this from LabVIEW by using an IO server. My problem starts at the beginning. I right click on my computer >> new >> I/O server >> Modbus
then in the popup window I select "Modbus ethernet" in the top right corner. I have attached this popup window. What is the Address in the communication settings section. The IP need to be entered at the bottom, so I have no clue what is the Address field is referring to.
Then I try to create bound variables... I see a huge list of registers, but honestly I dont understand how the address 360 I use in the standalone program translates to this list. Which one should I select from the list? Whatever I select gives me either 0 or FALSE if its a boolean. According to the documentation 360 is the relative address and the absolute is 400361. Actually there are a register list from 400001-465535, but if I select 400361-400362 I still read zero.
Reading only zeros and FALSE values... thats suspicious. Something is wrong.
Please help out with your thought!
Attachments:
modbustcp_OK.png ‏132 KB
modbus_config.png ‏56 KB
modbus_reg_list.png ‏98 KB

OK, just a quick (and dirty) test. Can you try this VI.
Kees
Attachments:
MB TCP test.vi ‏20 KB

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Attachments:
Master.vi ‏15 KB
Slave.vi ‏13 KB

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Attachments:
MB_TCP.vi ‏29 KB
MB_PLC.vi ‏28 KB

Dear J,
Check the state machine Architecture here.
1. In your acquisition if you got error in any system you close all TCP connections that is not right your other systems are working fine.
2. You go with parallel loop connection. For each PLC you run separate code with error handlers.
3. Check the attached VI for TCP Read. Same VI you can modify and use for your ModBUS operations.
4. In you Sub VI you are passing a constant cluster. I am not able to understand what is the use of case structure inside the subVI, In you code you are passing the constant so its always same.
As you done previously made 3 loops or VIs to read the data in a main VI. First try to made one VI with one PLC, remove your all bugs and errors and copy it 3-time with different-different configurations.
Thanks and Regards
Himanshu Goyal | LabVIEW Engineer- Power System Automation
Values that steer us ahead: Passion | Innovation | Ambition | Diligence | Teamwork
It Only gets BETTER!!!
Attachments:
Tcp Host.vi ‏28 KB

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Hi SmithD,
I would like to say thank you very much for making out time to respond to my queries. I have done as directed but still not getting result. Following the wire mode port setting configuration, I stopped the process and then selected the RS485/wire4 as the wire mode. On running the VI, an error pops up with the information that the Visa resource is Valid but the port cannot be accessed. I noticed that If I undeploy the shared bound variable the error does not pop up anymore. I concluded that maybe I was not supposed to have added the VISA configure Serial port in the first place.
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3.) Do I need an intermediate device between a Modbus device and the PC to be able to read its holding register?
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