485 Comm's SCU41

[Jacques 0]

Hi Hope somebody can assist, I need to transfer data from a Pic18f and a Omron CJ1M plc with and SCU41 card available. The Pic controller can communicate via 485. What do I need to send the Omron PLC serials comm's settings to. (No Protocol, Serial gateway etc.) not to sure what the best way is, I've started to read the W336 and w342 manual, according to what I can see there is many different ways of doing it, what is the best. (PCMR, CMND, RECV etc.) not to sure what will be the easiest. Can somebody please just point me in the right direction? I've managed to communicate a month or two back with a ETN21 and socket services, it there anything available for SCU41 just to manipulate the bits? Regards,

[PMCR 66]

You have 2 choices for ASCII comms on an SCU41. TXDU / RXDU instruction: Requires CJ1x-CPUx version 3 or later ,and an SCU41 of version 1.2 or later. You would set the port for No-Protocol Mode. All strings would be built in memory (DM, CIO, etc). You would use the TXDU instruction to send and the RXDU instruction to receive. This is easy for simple comms protocols, but gets cumbersome with complicated communications, checksums, etc. PMCR instruction: Can be used on any CJ and any SCU. You would set the port for Protocol Macro Mode. You would use CX Protocol to construct messages, steps, and sequences in a tabular setup. There are some advantages to PMCR (built in checksum calculation, timeout and retry settings, less ladder code), but also more complication. PMCR is not something that is easy to pick up on your own, but once you do, you will never go back to TXD/RXD or TXDU/RXDU. How complicated is the protocol, and what types of strings are required for the application?

[Jacques 0]

Application is very simple, Barcode reader read a barcoder reader to a pic and the PLC will be linked to the Pic. The pic sends the string to the PLC and the Serials PLC must read the value to a Data memory. At a later stage I would like to use multiple scanners to the pics, where I will use Unit number, but will then worry about the PCMR functions, for now only want to read the value.. Will this be possible. I had a look at the function, RXDU - it looks very simple but at C+1 it asks for the destination Unit address but I don't have a address for the PIC? in the PLC i'm using Port2 and the Unit number is #2.

[PMCR 66]

Sounds like RXDU would work just fine for your application. The 'Unit Number' in C+1 refers to the SCU41 unit number, not a unit number in the serial string.