Read from PLC 5 to another PLC 5

[Conor 4]

Hi all, I want to read B36:0 - B36:24 points from one PLC 5 on another PLC 5. Do I need to use an MG to do this. The reason I am asking this is that I have MG in the PLC 5 that I am going to do the read, but they are all used. I will need to put the processor into program to increase the size of the MG file. Also, can I just do a read on one and not have a corresponding read on the other. To clarify this. PLC 1 has status files for a process stored in B36:0 to B36:24. PLC 2 do a read of these files for purposes of displaying these status's on a Scada. Both PLC's are PLC 5. Thanks, Conor

[Guest]

you can add more MG locations by putting the processor into the "Program" mode ... then right-click the MG file and select Properties ... then set the number of "elements" to give yourself some spares ... note: for SLC and MicroLogix systems you'd need to go "offline" to add memory locations like this - and then you'd have to "download" the modified program to the processor ...

[PLCMentor.com 60]

conor, Make sure you add a few extra MG locations so you have room for future expansion - that is if your free memory will allow it. Generally you will have a fair amount of free memory and you should have spare locations for data types such as this. You also might want to check other memory types while you are down to evaluate if spare locations should be added there also. You will just need a BT in one processor. In fact, I like to designate one processor to handle all my reads and writes if possible. I have found that the PLC5 platform seems to be more stable with the message statements so I generally handle my messages between slc and 5's in the 5. With all this said, you have a maximum queue available for your messages so if you have a lot of messages, make sure you dont overload the communications queue. You should not have problems like that if you just have one mg to grab the data you indicated. russell

[Conor 4]

Hi guys, I was able to get the PLC in program for 10 mins from production. I increased the size of my MG, T4 and B39's. I also set-up the message read from PLC 2 as stated above, and I am now reading B36:2 -- B36:25 in B39:10 -- B39:33. Also, what is the Max and how do I check that I don't have overloaded the comms queue?? Thanks again.

[Conor 4]

Hi Russell, Can you tell me what the what the maximum queue available is, and also how do I check if I an overloading the communications queue Thanks, Conor

[PLCMentor.com 60]

Conor, Sorry I didnt subscribe to this topic and i just saw your question. I dont know the max right off the top of my head, but if you just have one msg then you wont have an issue. I am out of the office so i cant look it up right now. Generally not an issue unless you have a bunch of msg statements. If you have a lot then cycle them so that they all dont slam the queue at once. Russell