Rockwell Automation 2706-LV2P_LV2R_LV4P_LV4R DL40 PLUS USER MANUAL - Manual (Page 92)

Parallel Port Communications 7–12
Publication 2706-6.1
While the DL40 Plus is in Run or Debug mode, it regularly monitors
the 20 lines on the parallel port. Input data is only considered valid
when all lines remain unchanged for the time specified by Data Hold
Time in the Triggering Port Setup.
You must insure that any data sent to the DL40 Plus is held stable for
at least as long as the Data Hold Time. If there are any switching
delays on the lines, data must be held for the length of the Data Hold
Time plus delay time.
Since the DL40 Plus has a feature which prevents a message number
or variable from being entered more than once, there is no problem
holding data for longer periods of time. When a DL40 Plus reads the
data at the parallel port, a copy of the data is retained. If the next
reading during the sample interval is the same, the DL40 Plus will
ignore the second sampling, preventing the same data from being
sent to the queue more than once per scan. If you want to re–trigger a
message or variable, MS0–MS3 lines should be set to a minimum of
10 msec (plus switching delay time).
AC Sampling
To input AC into the Parallel Port, two AC to DC Converters
(Catalog Number 2706–NG2) must be used. When using a converter,
Using AC/DC Converter in the Triggering Port Setup must be set to
Yes. This will prevent Data Hold Time from being set to less than 40
msec. Conversion time must be added to the Data Hold Time.
34 msec NG2 conversion time
+ Data Hold Time (40 msec minimum)
Total hold time for your data
Sampling