Scrolling Text on an alphanumeric display

I have just recently set up an 8 segment alphanumeric display in our mill and i can get the text to show up on the display useing a AWT command in rslogix.. we have it linked to a controllogix proccessor. I have to send ascii to it.. but when I send a string with more than 8 characters it cuts the word off, and will not automatically scroll. what is the best way to go about makeing the text scroll ? thanks

How about programming the scrolling in the processor? For example, say you wanted to scroll "One great mill" text. Do the following:

write "One grea"
wait
write "ne great"
wait
write "e great "
wait
write " great m"
.
.

Adjust the wait timer to suit you.

Regards,

Justin

Try the equivalent in RS Logix:

FUNCTION_BLOCK TICKER

VAR_INPUT
N : INT;
PT : TIME;
END_VAR
VAR_IN_OUT
Text : STRING(STRING_LENGTH);
END_VAR
VAR_OUTPUT
Display : STRING(STRING_LENGTH);
END_VAR
VAR
delay : TP;
step : INT;
END_VAR

(* generate next ticker when delay is low *)
IF N < LEN(text) THEN
IF NOT delay.Q THEN
(* increase step for next tick *)
step := step + 1;
IF step > LEN(text) THEN step := 1; END_IF;
(* extract dispay from text *)
display := MID(text, N, step);
(* set delay timer for next tick *)
delay(in := TRUE, PT := PT);
ELSE;
(* execute delay timer *)
delay(in := FALSE);
END_IF;
ELSE
display := text;
END_IF;

Or swap it for a Vorne display. I used some of their units for a DL40 replacment at 1/3 the price. It could accept scripted commands easily pre-fixed to the original string to display variables in a wide variety of formats from canned text to ASCII messages. It had smooth scrolling, flashing, minimum display times, and more with a statement list type of language built into the free software so you could write your own functions to be triggered via the serial port or parallel interface.

We daisy chained two of these from a single PLC5/40 using the built in RS232/RS422 converters so that I could send them each unique messages. I am a big fan of Vorne, sorry for rambling on and on.

Is your display a "roll-yer-own"? Maybe you can modify the driver code and build in some commands in the device (do some string parsing in the display as you read its serial port), or use what was supplied by the mfg.

I guess I would decide based on how much CPU horsepower I wanted to spend on scrolling text vs. machinery control. But, if I had access to a RSLogix5000 Structured Text license, I would cut and paste Hokie's composition...

Paul

Thanks for fast replies

thanks for the fast responses.. I wont be able to try the structured text until tomorrow, i'm pretty sure our version of rslogix can handle it but not 100% sure.. as for the display theres not a whole heck of a lot of information i can get on it. It was created by a company called newnes in canada that just got bought out and am trying hard to find out if there are any ascii strings built in that i can use to scroll the text...

Hey in response to your function you gave me

IF N < LEN(text) THEN
IF NOT delay.Q THEN
(* increase step for next tick *)
step := step + 1;
IF step > LEN(text) THEN step := 1; END_IF;
(* extract dispay from text *)
display := MID(text, N, step);

can you please explain... delay.Q .. everything else is makeing sense.. i dont have a structured text license for RS logix.. but i can make that all work with ladder logic. used to program structured text so can convert it to instructions in rslogix.. just not sure what delay.Q is

Delay is an instance of TP, or a Time pulse. RS logix does not have a time pulse specifically, but you latch in a timer with the TT.
Delay.Q is the actual pulse bit (boolean).
This function block does not wrap around the beginning of the message as the end goes by, but it would be easy to concat the beginning part of the string as it wraps around, if you wanted.

Thank you

Hey thanks a lot, made your function block into ladder logic and it works perfectly like you said the front does not wrap around but that shouldnt be to hard to get working with what youve given me.. thanks again !