The PLC switches from one to another when trying to go online

hi every body !

i have a problem. we r using a network of 3 PLCs connected to HMI TP170a. The configuration file is attached here. Data communication is used using the DBs. But I could not understand what is the name of this type of configuration. Obviously it is not a redundant one as not using IM153-2 card. When one PLC (which is named ALNAR2, suppose) fails, the other one ALNAR3 takes over and vice versa.

can any one help me out in explaining the type of communication used here. If any documentation available for such type of network configuration, please let me know. This is supplied by one of our plant supplier.

Recently I am facing one very big problem. Whenever I am connecting my LAPTOP to the PLC and trying to go online, the PLCs switches from one to another. The switch over is not bumpless. So the running equipment stops and start again with a time gap of 5-10 secs. If any body has faced this type of problem, please help me out.

hi all

i did not get any reply from anybody. i once again request if any body is having any idea, please share.

due to this problem i am fear to do any job on that plc.

i m attaching the back ups files, for ref.

do to problem in attaching i m unable to attach two more files, i will try to attach if any body needs, please let me know

please let me know if any body can look into the matter to help.

very unique problem ? now i fear connecting my loptop to plc to go online to study the program.

with thanx in advance.

sanjay

This is not a PLC I am familiar with. The program looks like Siemens S7, is that correct? Please explain the hardware a bit more - we have LOTS of Siemens fans here.

TM

Hi,


Is it possible that your PLC's are connected via an MPI network?
You say :

Whenever I am connecting my LAPTOP to the PLC and trying to go online, the PLCs switches from one to another

Click to expand...

I presume you are connecting to one of the two PLC's S7-315? Is it possible that your laptop uses the same MPI-adress as one of those PLC's?

Hope this get you started.

Rudi

From the diagram, it looks like it is an MPI network.
Is the cabling between all the nodes made correctly ?
Profibus cable + connectors must be laid in a "daisychain". The 1st and last node in the physical MPI network must be terminated (there is a switch in the connector for that pupose).
If termination isnt installed correctly, it can account for the comms going wrong.

I am guessing that the original programmers has made a kind of watch-dog with a very short response time, leaving no room for errors.
When you attach your PC, either the comms is stopped completely (because of the cabling problem mentioned above), or there is a increase in the cycle time of the MPI token rotation (normal when adding a node to the MPI network).

If you have problems with the system, then contact the original supplier of the equipment. They must solve the problem or assist you in solving the problem.

hello guys !

thanx for reply. its using MPI network and working fine. the only problem is coming when i m trying to go online. also my laptop is using unique MPI address "0".