from post #7:
Techqueen said:
when i type in r72:0.1 it reverts to the len which makes sense then i type in the r72:0.2 it reverts to r72:0.pos, which is also correct, when i type in r72:0.0 it says it is not address in word level, i think it's a bug in the program??? what do you think??? i got on to the rockwell site and left a message maybe they will get back to me. it doesn't look like rslogix5 is going to let me clear this file the way it used to be done. i've tried the mov going into r72:0 and is does the same, even if i use r72:0.0.
I'm still a bit unclear on this. Is the intent to clear the 'buffer', that is, the collection of words which was sent with the message instruction? Or, is the intent to reset the control structure (R72:xx)?
If the former then if a MSG instruction is used there is no absolute need to clear the buffer - the MSG control bits will handle the internals. All you need do is load/format your outgoing data and trigger the MSG (make the rung go true).
If the buffer absolutely, positively must be cleared, there are any number of ways to do this.
If the latter, there's a way to clear control files also. The elements in the control word (pos, len, ctl) comprise a
structure. The programmer is allowed direct access to only two of these elements, POS and LEN. To access CTL you need a separate file instruction with LEN=3. As in;
new control len source destn
FLL R6:73 3 0 R6:72.POS
<excuse the formatting, this editor will not allow multiple consecutive spaces>
I don't remember which element is specified in the destn, you'll have to experiment or wait 'til I refresh my memory at work.
With a properly built FAL, you could also pull out the three elements into another three words for observation.
On a side note, the RES instruction does work with control registers. The only thing I've found it won't do is clear the
INhibit on an FSC instruction