MicroLogix 1500, ASCII instructions

Hello Guys\Gals,

I am trying to write to a simple display from my Micrologix 1500 processor's serial port. (LRP, so I have 2 channels, the channel I'm using is configured for ASCII).

The display requires a string of the form <SOH>string<CR>. I can place the string into a string data file in RSLogix500, ST9 for example.

I can use an AWA instruction to append the <CR> control character, however I do not know how to send the <SOH> control character before the string. From talks with Rockwell, it sounds like if I put a ^A in the string, it will not be interpreted as a control character but rather as just a part of the string. Rockwell suggests that there is no way to add a control character before the string with a ML1500.

Do you know of any work-arounds or have any suggestions? Thanks!

Try the ACN instruction. I have several serial label printers controlled by ML1500s, and I use this to build the data string to send to the printer.

For example:

ST9:0 will equal your control character <SOH>
ST9:1 will equal your string
ST9:2 will be the destination of the result

After you execute the ACN the destination should contain: <SOH>string

If you repeat this with ST9:2 and a string that contains the <CR> into antother destination you should get <SOH>string<CR>

I hope I explained this correctly.

/Shrug, I just tried it here, using ^A works fine. Make a single string with the "^A" combination, it should show a length of 1. If the combo were interpreted as 2 characters, it would show a length of 2.

Now, just use ACN to combine that, and your "Send String" into another one, append the CR, done.

Ok. I will try what you two have suggested. Another question that I have is that the display is set for 8 bits per character and 1 stop bit. I have seen how this can be configured in other processors, however I do not see any options for this in the ML1500 ASCII setup.

Any thoughts?

The manual says that 1 is the only setting for stop bits. I would expect that there would be 8 data bits and no parity by default as well.

Paul