CJ1 - CJ1 PLC over Serial

[Nibroc 4]

Hi, Firstly - if your PLC's are CJ1M series (not CJ1) you should look at using the built-in serial link. If not: I haven't personnally used SEND, RECV via serial (but have via controller link, ethernet etc). The 'FA' denotes that the message is FINS protocol, (encapsulated within hostlink). See Omron manual W342 for help with the internals of FINS protocol, and C - Mode (which is hostlink / sysmac way) The port set to RS232 (non protocol) will not respond automatically to a hostlink/fins data packet. The port should be set to hostlink, toolbus or possibly serial gateway. The serial ports are mapped to a network using the routing table tool - they may be set to a network number by default? Both Master and Slave PLC's should have ports set to the same config. I would configure one PLC to behave as the 'Master', and use both SEND and RECV commands from this end only - otherwise you will have collisions which the serial cannot deal with. The 'slave' PLC should respond automatically with no special programming. I suggest using the Omron function blocks CPU010 (Send data), and CPU011 (Receive Data) instead of the ladder equivalents. They are much easier to use and save much time (although they do use the ladder functions internally you do not need to worry about them). These are some pointers only - I have not actually used send/receive over serial and do not time to set up a test rig - it will work ... Tim Corbin Edited 13 Apr 2008 by Nibroc

[BITS N BYTES 66]

How much "data" do you want to send. PLC Links is the simplest, fastest, lowest cost method of exchanging data between CPU's. If necessary this can be increased by encoding the PLC Links messages. For example the first word can be used to identify "what data", "what message" is being sent. The receiving PLC then interprets the data based upon the value of this received word. The permutations are limited only by your creativity in developing software for your application. Good luck.

[james_applied 0]

I have been trying to do this. It seems as if the PLC you are sending the message to does not respond. Possibly because the COM port does not have a node address. If you have Ethernet ports then you can use these with the SEND and RECV command without problems. Else you may have to use PC Links or do what i did and write your own comms protocol as i wanted to exchange about 300 words.

[Nibroc 4]

... What model of PLC are you using - are they CJ1Ms ? If so, have you looked at using the built in serial data link function. Do you have the manuals you need ? The TXD function can also send hostlink data, have a look at this instruction in the manual. The TXD / RXD functions can be used to send protocol free data with the PLC ports set in 'RS232' mode. It may be easier to implement this method. (unless you need error checking). SEND / RECV should work, however I don't have a test rig ... Nibroc