RS422/485 communication

[Guest Aldo]

hi everybody, i used CPM2A, 1pc NT21(as slave), 2 pcs 3g3mv(slave), through the NT i could to change the speed reference for those Inverter and monitoring the speed of those Inverter, Do i have to used CX-Protocol for that system? because this is first time for me to make system that using Communication through RS485, Could you give me a sample ladder program for that system above, because i have read the manual ( host link communication) but i can not to understand, and how to set the parameter Thank's 4 your help

[Sleepy Wombat 27]

You will not be able to have the screen on the same netwok as the drives..... May i suggest to save a lot of head aches...... Buy 2 X CPM1 MAD01 units this will give you a total of 4 analogue inputs and 2 analogue outputs. Of course connect the PLC analogue outputs to the drives Freq Ref inputs to control their speeds and use the analogue outputs on drives to drive the analogue inputs on the PLC to give speed feedback. Program the screen to both display and control the anlaogue outputs to control the drives. And also to display the actual speed of the drives...writing a protocol to achieve this simple scenario is not worth the time and effort. The price of the MAD01 cards will surley pay for themseleves as opposed to the required protcol developement time. I always remember the KISS principal -- Keep It Simple Stupid Edited 12 Dec 2003 by Sleepy Wombat

[Guest Aldo]

Thank's alot 4 your quick respon, sleepy wombat, of course, it's easier using i/o analog for drive the Inverters, but if i always using i/o analog, when i can improve my experience? so i need to learn how to make communication using RS232/485. i think in the future i will find many system using RS485, so i wanna know them. Or have you a reference about how to make communication system using RS485

[Sleepy Wombat 27]

For further ideas on comm's look at this thread. Comms's thread....

[Jay Anthony 118]

CX Protocol is not an option with CPM2A. This is reserved for the CS/CJ series of Omron PLCs. What you need to look at using is the TXD and RXD commands in the CPM2A. Use the RS232 port for the NT21S connection. You need a CPM1A-CIF01 adapter to convert the peripheral handheld port to a second RS232 port. Then you will need a NT-AL001 RS232 to RS422 adapter to convert the CPM1A-CIF01 RS232 port to RS422. Do not be tempeted to substitute a CPM1A-CIF11 because the RS4222 only works properly with Hostlink. The 3G3MV inverters use RS422 and Modbus commands. Look at Sleepy Wombat's link and follow the thread on how to use TXD and RXD commands. Then come back and ask what you need to know about Modbus (the FCS is not the same.) It's possible - the question is "Are you ready to undertake it?"

[Guest Aldo]

Thank's so much 4 your respone sleepy wombat & Mr jay, i will try what do you suggest to me, because this is first time for me to make program using rs485 ( TXD & RXD function ) So i need to learn from the expert, like you are, Thank you so much once again