Sign in to follow this  
Followers 0
dWiseman

1769-ASCII Read Issue

2 posts in this topic

I am trying to set up a 1769-ASCII card to read data from a Honeywell Intermec printer.

I am trying to monitor the LTS sensor so that I do not print duplicate labels.

Using hyperterminal when I send the command (PRINT PRSTAT) I receive the status bit then OK. it would look like this:

*****

0

 

OK

*****

When the first part of the message is 0 the label is taken and if it is 2 the label is still present

When I send the exact same command via the 1769 Card I ONLY receive the Ok portion of the message. I imagine the card is reading the 0 then overwriting it with OK immediately after.

I am sure the data is getting to the printer as when I send commands to print a label it works flawlessly.

The cable is wired as follows:

2-3

3-2

5-5

7&8 connected on PLC side.

Any insight as to what could be happening would be greatly appreciated :).

 

Cheers,

dWiseman

Share this post


Link to post
Share on other sites

If there are carriage returns and line-feeds at the end of each of those lines, then I agree that the module is simply over-writing the input buffer each time it receives a line with a delimiter, and the PLC isn't grabbing the data until after the buffer has been over-written.

Maybe you could configure the card for "Ignore Delimiter" on received strings, and set the Rx Timeout to an appropriate number of milliseconds in order to deliver the whole string "****<CR><LF>0<CR><LF>OK<CR><LF>****<CR><LF>" into the input data table.

In the CompactLogix, it's relatively easy to search a string for another string with the FIND command, so you could look for "OK" within that string.

I remember running into a similar issue with a POINT I/O ASCII module and having the problem that when you didn't use a delimiter, the only way to declare the end of the incoming data was a fixed buffer length.   The 1769-ASCII allows you to use a delimiter, or a fixed buffer length, or a timeout.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0