VME chassis with Rockwell L55 Processor

[raul_vaze]

Dear All ,

WE have a existing VME chassis that is communicating with Motor manager on modbus . I am not much aware of the VME system , but what i could see that there are 3 ports , two of which are connected to Motor Manager on Modbus , where as one serial port is connected to L55 processor serial port .

Now we have task of removal of the VME chassis and putting Prosoft modbus cards in the L55(v11) processor chassis and those prosoft cards will communicate to the Motor Manager on Modbus (Serial 485).

Does a VME system has a card that is compatible with L55 since existing is communicating with it ???

How much memory will the prosoft card consume if it is added in the L55 processor ??

Does a VME system has a card that can talk to motor manager on modbus and at the same time talk to L55 processor on serial ???

Please help me as i am not much aware of VME system

 

[Ken Roach]

VME is an old industrial computer bus standard. There are hundreds of different computer and control modules that plug into VMEBus backplanes, including an old version of the PLC-5 processor.

You will have to determine exactly what those VME modules are before you can migrate their functionality to ControlLogix.

Prosoft MVI56 modules are not extremely memory-intensive, but I would have to create an old project with v11 to tell you exactly how much program memory each instance of the sample logic takes up. You can do the same thing yourself with your existing RSLogix 5000 program and the sample code from ProSoft. Because your controller is very old, you will have to use the original sample code instead of the modern (V16 and later) Add-On-Instruction based sample code.

 

[raul_vaze]

Hi Ken ,
Just checked out that the existing system is CMAC VME processor ( from Switchgear & Instrumentation ) which has i guess 3 ports ( one is RS-232 , another is Modbus serial i guess ) .. So it communicates with L55 processor on the RS-232 port and communicates to the Motor Manager on Modbus ports.

Can somebody provide information on the CMAC VME unit or any manual that describes the detail of it .. I tried a lot searching on it but couldnt find it ..

 

[narcilla]

Hi Raul,

The CMAC processor is basically a modbus interface which communicates the data it gets to the VME-PLC via the VME backplane (shared memory). The MCM is the same although for a different platform.

We changed all our Fume Treatment plants PLC5-VME's to CLX when I was still in Dubai and used the ProSoft 1756-MCM to communicate with the motor managers. We used the AOI that ProSoft provided and everything worked well. The instruction manual details all that you require as far as setting up the card. Have the internal memory addresses of your motor manager handy so you can send the appropriate commands. The CMAC configuration file will be handy as well as it will let you know what details it is trying to fetch from the motor managers (if you want to replicate its functionality). We added more data but you have to remember that being a serial link, modbus can be slow so limit the data being fetched.

Just a note, if you are using S&I Motor Managers which is highly likely since you have CMAC processor, then please note that the input switches as read via Modbus is reversed. We found this out when we used a GE motor manager which has the bits set correctly.

 

[raul_vaze]

Hi Raul,

The CMAC processor is basically a modbus interface which communicates the data it gets to the VME-PLC via the VME backplane (shared memory). The MCM is the same although for a different platform.

We changed all our Fume Treatment plants PLC5-VME's to CLX when I was still in Dubai and used the ProSoft 1756-MCM to communicate with the motor managers. We used the AOI that ProSoft provided and everything worked well. The instruction manual details all that you require as far as setting up the card. Have the internal memory addresses of your motor manager handy so you can send the appropriate commands. The CMAC configuration file will be handy as well as it will let you know what details it is trying to fetch from the motor managers (if you want to replicate its functionality). We added more data but you have to remember that being a serial link, modbus can be slow so limit the data being fetched.

Just a note, if you are using S&I Motor Managers which is highly likely since you have CMAC processor, then please note that the input switches as read via Modbus is reversed. We found this out when we used a GE motor manager which has the bits set correctly.

Hi narcilla ,

Can u please tell me whether another processor was there in addition to CMAC processor and why is it connected to CLX processor on RS-232 and can u please share the manual if u are having ?? Pls help

 

[narcilla]

Raul,

Sorry, I misunderstood your setup. The CMAC has no way to send data to the CLX aside from the RS232 port. Our setup before has PLC5-VME on the same rack as the CMAC processor so the exchange is on the backplane. We didn't get proper documentation for our setup so we had to decode the PLC code and the CMAC configuration. Good luck getting a manual for the CMAC.

In your case, check the receiving CLX for the serial exchange. It should show what commands it wants executed on the CMAC. Is it possible to send the CLX code so I can have a look?

 

[narcilla]

Raul,

Sorry I didn't answer your last question. The CMAC is a Modbus interface with some added functionality optimized for motor control. It needs a separate processor to actually perform the plant logic. In our case it was PLC5-VME and in your case a CLX. The actual start/stop signals are generated from the CLX and sent to the CMAC thru the RS232 which then sends out the modbus commands to the desired motor manager.

 

[Oceansoul]

We used to have a CMAC VME PLC5 processor. As has already been said in this post, we used it with a number of S&I Motor Manager 2's. The VME processor set start commands to the drives and read data back from them. This was then passed to a supervisory PLC5/80 over DH+ which communicated with the SCADA.

Unfortunatly this was before my time, as when i started the VME had just been replaced by an SLC504. Still talking DH+ to the PLC5/80, and using prosoft cards to talk to the motor managers.

I've checked the code in both the VME and SLC and its very similar. I however have no idea how it worked, sorry.

Interesting that this seems to be a setup thats replicated around the world.