Omron CP1H PLC Programming Serial

Hey all,

This is a great site. I'm fairly new to PLC programming, but learning quite quickly.

My issue is that I don't know where to begin with structuring a program that will for the most part use serial strings to control several motor drivers via RS232.

The big concern is that the CP1H can only use one TXD command per cycle which means that I need to write code to sequence the commands to the driver. I have been able to successfully sequence a basic group of commands using shift registers, however, I am not sure how I'm going to sequence larger/more complex commands.

Later in development, I will need to send queries for position data and motor torque data. This received data will be displayed and then additional move commands will be sent afterwards.

Should I be looking into programming using cyclic tasks, interupt tasks, the built in stepping/jumping functions, function blocks, or what?

PLCS just don't seem to be the right tool for manually controlling motor drivers via RS232 because of the one command per cycle limitation.



Just to be clear, I don't need help making the devices communicate. I know how to send commands. I just don't know how to structure and sequence my program.

I was thinking about this problem more the other day, and I came to realize that the Omron method of serial communications is just not ideal for sending strings of separate commands because it does not queue up all the commands given in one cycle, but only sends the first one.

Does anybody know of any control solution that would allow me to write control logic in such a way that in one cycle, all these commands could be queued up, but not necessarily executed immediately? Perhaps a PC based controller with a small touch screen or another plc brand?

You can queue up a number of TXD commands in your program - use the "Send ready" flags. This will release your transmits in the sequence they occur in your program.



For the CP1H - A392.05 is for port #2 & A392.13 is for port #1.

Alternativly have you considered adding the CJ series serial comm's card and using the protocol macro functions??

I just got the cj1w today at the trade show. I will look into protocrol macros soon. Hehe. I'll probably need to really read up on this stuff.

I don't really know how to structure my program. In essence I'm trying to program a CNC machine.

Hi, Cx-Protocol is not the easiest thing to master but once you get the hang of it its not so bad. The easy way is to get somthing simple that some one else has done & see how the protocol was assembled.


PS - you can fit the CJ cards on the CP1H PLC.

Best of luck

Here is a link to Modbus RTU master and slave written in CX-Protocol. This may help you hopefully.

http://forums.mrplc.com/index.php?download=259