how to control and monitor omron plc from labview

[jacintha]

Hi,

i am able to make the plc communicate with labview 2009 using NI OPC Server and DSC Module via ethernet but i do not now to control and monitor plc boolean data from labview.

the plc i am using is Omron CJ1M CPU11 with CJ1W-ETN21. I am still very new to labview and i hope somebody can help me out with this and give me some advices on how to proceed. it should also be noted that i cannot change the status of the tags directly from NI OPC Server itself. 

Below is the simple circuit i would like to use as a starting point for controlling and monitoring plc data from labview:

Thanks in advance for the help. 

[KateB]

1. You need to set up OPC server to CJ1M communication following the step in  Start>>All Programs>>National Instruments>>NI OPC Servers>>NI OPC Servers Help>>Omron FINS Ethernet>>Launch Driver Help.

2. Configure I/O Server binding to NI OPC Server.

3. Creating shared variable binding to NI OPC Server tags, and use these variables inside LabVIEW program to communicate with CJ1M.

#2 and #3, please follow http://zone.ni.com/devzone/cda/tut/p/id/7450

[jacintha]

Yes, i have configured the communication between plc, opc and labview with the dsc module like the tutorial. i can also monitor the change in values of the opc tags when i change the states of the switched in cx programmer. 

however, i do not know how to write data to the plc from labview. by writing data, i just mean to change the status of the control switches of the ladder diagram (force on, off) hence manipulating the output of the ladder diagram.  

[KateB]

1. Drag shared variable you create in LabVIEW project to block diagram.

2. Right click on it>>Change it to write.

3. Wire the value you wish to write to a shared variable.

[jacintha]

i tried doing a simple write before but it still does not work. is there a tutorial/ sample vi that i can learn from?

[KateB]

Please attach the whole project include opf file (OPC server configuration)

[jacintha]

ok i have included the project files and the opc file as well. 

[KateB · Accepted solution]

You can read only from the input, cannot write.

For output, you can either write or read.

However, if you've a ladder controlling that output line.

It'll have a conflict.

[jacintha]

thanks KateB. i finally can see it for myself. can write/read to output tags but can only read to input tags using datasockets. i just wondered why is it like that? could you explain it to me? 

[b.headley]

I had a similar problem with a Koyo DL06-DR PLC.

The solution was to build a ladder input multiplexer: the mux control bit is an internal flag. This flag gets cleared during the PLCs first scan and can be set/reset by the PC to steer where the PLC inputs would come from (either direct inputs or from PC control bits).

The outputs can be read/written anytime by the PLC or PC, so the PLC code is written using stage programming techniques, with set/reset instructions being placed only where needed.