ASCII module

We use a lot of A-B 1771-DA ASCII IO modules to get barcode data in a system recently converted from PLC-2/30's to Softlogix. Now that the programs are in a more readable format I've been going over them with an eye to cleaning up a lot of original logic inconsistencies and 'improving' things with the features available in SL5, ie. structures.

Anyhow, in my wanderings, I read up on the ASCII module and learned some things and got confused about others, namely, the module handshake setup. The manual states that the module toggles READ DATA AVAILABLE when new data is received (data from the device terminated by an end-of-string delimiter) or a change in module status occurs. Monitoring the program shows that READ DATA AVAILABLE is continually cycling, as is the corresponding READ DATA ACKNOWLEDGE sent in reponse by the program even with no new scanner data coming in.

Does anyone have any clues why the module status would change, assuming this is what is happening, without new data received? It's not a big deal, the programs work normally, it just seems like a lot of busywork to me.

Secondary question: What constitutes a change in module status?

WELL I REALLY DON'T HAVE AN ANSWER FOR YOU. I CURRENTLY HAVE SOME BAR CODE READERS VIA DATALINK DL 3000. IT USES A DH+ ADDRESS AND INSTANTLY WRITES THE DATA DIRECTLY INTO THE INTEGER THAT YOU SPECIFY. NO PROGRAMMING IS REQUIRED. WITH MOST MODULES YOU HAVE TO USE BT'S OR MSG'S ECT. THESE ARE SO EASY TO SET UP. IT TOOK ME NOT EVEN AN HOUR TO SET ONE UP AND THAT WAS IT. I WENT BACK AND DELETED ALL THE OLD LOGIC FOR THE OLD READERS. I HAVE NOT HAD ANY PROBLEMS AT ALL WITH THE 3 UNITS I INSTALLED.