PLC to PLC and to PC Communications

[Guest akinsey]

I have several production lines that each have 2 PLCs that do not communicate to each other except for a couple of I\Os. All PLCs have A2USH CPU I am needing to read the data registers of one PLC from the other one or transfer the data from one PLC to the other. I will also be needing to frequently download this data to a PC. What is the best way to set this up? And of course, my real problem is time, my boss has already commited to having this done very soon, and I have no experience with Mitsubishi PLCs. I have already programmed in the counters for each PLC, just have to get the data from one PLC to another so I can have yield displays along with production counters on the HMI. Any advice is appreciated. Thanks, Adam

[andybr 5]

There are many ways of doing this with Mitsubishi A Series PLC's. My preferred method would be to have an ethernet card in each PLC rack but this involves quite a lot of code and a good understanding of what you are trying to do. Another option would be to use Melsecnet-B for sharing data between the PLC,s and an ethernet or serial card from the network master to the PC. This uses more hardware but would be much simpler for someone with limited experience. Andybr

[waynes 8]

If you don't want to use network cards you can also use the old fashion way of multiplexing. Simply get some cores between you plc's and send the info you need. Connect the master, like andybr said, to the pc and read the info via the serial interface. Most scada's/ opc servers have this communication protocol built-in.

[panic mode 246]

actually there is very little to be changed in PLC if you are adding ethernet cards.(no PLC logic is needed unless you want PLC to initiate connections).

[andybr 5]

Panic Mode As I understand it PLC code is required to open a port on an ethernet card for an A series processor even if this is only used for connection to a PC (SCADA etc). Sharing data between PLC's also requires code for this as well as code for the actual messaging. I am not an expert on the Q series and things might have changed but if it possible to use an ethernet card on an A processor without the above code I would be interested in hearing about it. Andybr

[Big Country 3]

I haven't tried this but could you take a few inputs and outputs from each plc like he has now, map them to a data register and read them however you want? Kind of a crappy way to do it but if he has a deadline and no experience with communications it might get him by until he has more time.

[panic mode 246]

i didn't see many A's with Ethernet lately and I don't have one here to try it out so I'm not 100% sure. If my memory is good on QnA and Q I was able to simply plug the card, and assign address and that was enough to go online and read/write plc memory with a VB program using MX-Components.

[waynes 8]

panic mode, you are right regarding the system Q/ QnA. Most configuration can be done in GX Developer. You can even set up your ports to connect to a specified IP adress and make it an 'Active' connection, ie. the plc will handle the comm port (opening and closing). The A series requires the user to code every single port and handle all connections. I think akinsey should consider using the melsec net b interface. This is relatively straight forward to set up between the plc's.

[Friday 0]

Hi, Use any SCADA (OPC Client) and OPC server to make communication between PLCs and PC is an easy choice and flexible for future extending network. If you can use VB, VB.Net,C# or VBA, you can use OPC ActiveX control instead of SCADA software. Its cost is lower and flexible to your requeirements. You can use Ethernet or Serial OPC Server for Misubishi Q Series. For OPC Server using with Q Series, pls visit KEPWare . An OPC ActiveX control with unlimited tags capable I know is COPC32.