Sore head

[kennyb]

Hi, there. I was hoping someone has experience of embedded Siemens systems. What I've got are 19 IPCs running Step7 WinLC modules all tied togethe ron a nice little ethernet hub. I'm trying to make minor changes to the code on one M/C (the line controller) but I am unfamiliar with how this "PLC" gets info from the other 18, which are high speed robots. Up till now I have only set up comms on MPI between PLCs and used Profibus for instruments and drives. I am looking for SFCs, SFBs or common DBs but not much luck so far. The code is pretty damn big and although well commented it is commented in some kind of mad mnemonical(is that a word?) system known only to the originators. Hope someone has a few pointers, I've already crashed the LAN twice.

 

[JesperMP]

Reading your post, I interpret your system like this:
1 "master" PLC commanding 18 "robot slave" PLCs.

You should check the hardware configuration for the whole system first. I would guess that the network is set up as Profibus DP, with the robots appearing as slave IO. That means that there is no communication FBs or FCs, it all happens in the hardware configuration.

Then again, I dont understand that "all tied together around an ethernet hub". How ?

 

[kennyb]

Jesper,
it's not that simple. I'm at home just now but if memory serves it goes like this - 19 industrial PCs are running winNT. Under this we have Siemens S7 WinLC - this is the "PLC". The hardware config for each M/C shows a profibus DP. For the 18 robots this has ET modules for IO and a MicroInnovations HMI. For the line controller it has ET IO an HMI and the VSDs for the conveyor systems. All 19 DP systems are separate. The comms between each robot and the line controller is done over ethernet. This is my problem - I don't know exactly how, never having played with this before.

 

[JesperMP]

I was wrong then. Your setup looks like this:
19 PCs with WinLC, each connected to ET200.
1 PC is "line controller"
18 PCs are "robots".
All PCs connected via Industrial Ethernet.

I think that the programs in each PC must include some standard FCs to handle sending and receiving messages over Ethernet. The problem is that the FCs can be renumbered so it is not the original. That makes it hard to search for them.
Try this: In STEP7 manager, open the window with all the blocks and expand it to show details.
Look for blocks with "SEND" or "RCV" in the name, or blocks with family designation "COMFUNC". Then use the cross reference utility to find where in the program the FCs are called.

 

[RRobbins]

I would suggest getting the equipment mfg to make a drawing, showing all of the communication between work stations and what data is being sent between them. There can be a number of things going on that you are not aware of. There are a number of ways to setup that communication also. The communication between the robot is most likely the same from the controller to the robot, on each station. He needs to show you how that works also. If you can't get him to do it for free, you may have to pay for a service call to get the changes done and use that time to get the overview of the comms from the service guy. It sound like you should leave this one, for time being with the factory guys.