Serial Comms w/ Micro850

jordanat2012 · Aug 8, 2018

Hi all,
Pretty new to PLCs, and I think I've gotten myself in over my head. I'm trying to get an AB Micro850 to communicate via RS-232 with an audio module. I've got very specific ASCII strings that I have to transmit, but I can't seem to understand how to transmit them.

Anyone able to help me out?

shawn_75 · Aug 8, 2018

I've never used CCW or any Micro series PLC, but I suggest you use PuTTY or another similar program to transmit the strings from your PC and verify that the audio module reacts as expected. Most serial comms with non industrial devices I've worked with required a carriage return or another special character to signal the end of the transmission. PuTTY will help you determine the exact data to send for the response you want. Once you know exactly what the device needs to receive, getting the PLC to send it should be relatively easy.

What audio module are you using.

jordanat2012 · Aug 8, 2018

Thanks for the lead Shawn. I'll check out the PuTTY option.

The audio module is a Goetting HG G-31500-A. Datasheet attached. I had to have it shipped from Germany - seems to be a pretty specialized unit that I couldn't find state-side.

I've also attached the user manual. I had to translate it from German, so excuse any errors in it.

damica1 · Aug 8, 2018

Read chapter 6
https://www.engr.siu.edu/staff/spezia/NewWeb438B/labs/2080-rm001_-en-e.pdf

Firejo · Aug 9, 2018

The "AWT" function block is what is used in CCW to write ASCII characters to external devices. I've never done it in CCW but the help file in CCW is pretty good at explaining it.

shawn_75 · Aug 9, 2018

How many audio files do you intend to play? If it's a lot, you may want to build your command inside the 850. If it's only a few, just store them as strings. What I don't know is how to enter hex data into a string in the 850. In the MicroLogix series, you would enter /02 for the STX character because if you type "STX" into the string, "53 54 58" is what will be transmitted over the serial port when the device is looking for 02.

shawn_75 · Aug 9, 2018

Also, disregard what I said about Putty. That device requires non printable characters "stx and etx" and I don't think putty can send those.

jordanat2012 · Aug 10, 2018

I’ve looked into AWT, and thought that was the best solution. But then I started doubting myself, thinking it required some blocks beforehand, but I wasn’t sure what, if any, are needed. Does anyone have a sample that uses AWT?

I’ve only got 12-14 ASCII strings, so I plan to just hard code them as strings.

shawn_75 · Aug 10, 2018

Just a quick note. I didn't have any software in front of me to verify yesterday, but in Logix500 to tell the AWT to transmit string data as HEX, you use a backslash and not a forward slash as I said before. I suspect CCW will be the same. In other words, in your strings you'll use \02 as the first character. You can't just put "STX" in your string.

jordanat2012 · Aug 11, 2018

Wanted to ping the group again - would anyone be able to help provide a piece of sample code that shows how AWT is used?

brendan.buchan · Aug 11, 2018

Rockwell Sample Code library.

Search for 'Micro 800', first result is a UDFB and sample code for read/write ASCII.

http://www.rockwellautomation.com/global/sample-code/overview.page

damica1 · Aug 11, 2018

How about you provide us with what you already have and I'm sure someone will be able to point out needed changes.

Be sure to read chapter #6 from post #4 because if you don't you will not get you project completed.

There are several things you need to understand before attempting to read/write out the RS232 port on a Micro820 or 850 plc.

Serial Comms w/ Micro850

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