Jump to content

Virtual cable connection

Recommended Posts


I'll try to as precise as I can because it is quite complicated.

I have V130-33-R2. It has one COM port which is configured in ladder to Modbus RTU.

Communication is ok - I read PLC via modbus.

When I want to update programme in PLC or just have online look on registers - I plug in the cable and VisiLogic do some magig and reconfigures the COM port back to PCOM mode from Modbus.

And here everything is ok also.

I have such a installation: V130 -> via cable -> GPRS modem -> via GPRS -> SCADA server -> SCADA system

And I can read registers via Modbus - everything's OK.

The problem starts at this point (I'll just mention that this works with U90 Ladder and Jazz or M-91 PLCs).

When I try to update program remotely like this: My PC -> via GPRS -> GPRS modem -> via cable -> V130

It is trying to connect and is failing - I get info as if the cable was not connected.

I tried to send to SI 115 value 0 to change it to PCOM mode (from 1 which is Modbus) and it was ok - as I saw in Info mode in communication - it had changed.

But it didn't help - still couldn't connect.

Any ideas how to do that?

Link to comment
Share on other sites

  • 5 months later...

Solution - if any one wolud have the same concern.

What I did was putting another piece of code to set the Com Port into PCOM mode. The code was triggered by MB which I could set via ModBus.

So it works like this:

PLC is running and is transmitting data with ModBus via GPRS.

When I want to connect to PLC with VisiLogic I just send instruction/order through ModBus to reconfigure Com Port info PCOM mode.

And I can connect to PLC.

After I finish working, I just reconfigure the Com Port to ModBus and disconnect.

I have also added a timer (1 hour) which starts after I reconfigure the Com Port to PCOM.

When it is done - Com Port is reconfiguring to PCOM automaticlly.

It is just in case I forget to reconfigure Com Port to ModBus by myself.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...