Issue
141 April 2002
Replacing
Relays with Ladder Logic
Part
2: The T100MD-1616+
by
Fred Eady
Recording
the Music
Now
that everyone is in tune, harmonies from the PLC duet
are wafting across the Internet. The T100MD-888+ and T100MD-1616+
not only control things, but are also capable of monitoring
devices. There are times when someone wants to know just
how things are with a PLC in the form of a report or spreadsheet.
Normally, that means more work for the poor PLC programmer,
because you must resort to writing scripts or programs
to capture the desired data. However, that’s not so here.
|
(Click
here to enlarge)
|
Photo
6—The selected location is S2, the Florida room. In
the upper right window, one read action (A1) is defined
for PLC 00. The lower right window is a detailed view
of action A1. The result is the Excel window, which
shows LED4 (0x08 in cell B1) was active at the day
and time shown in cell A1. |
When
all of your PLCs are humming, TRi-ExcelLink allows you
to monitor and collect data from up to eight PLC sites
into Excel spreadsheets (see Photo 6). Basically, Tri-ExcelLink
uses read and write actions to gather data from the multitude
of PLC variables I mentioned earlier. For instance, you
could read Output[1], which is the full complement of
16 outputs on the T100MD-1616+, and then write the 16-bit
value representing Output[1] to memory location 2000 (DM[2000]).
Then, you could set an action in Tri-ExcelLink to put
the contents of memory location 2000 into a time stamped
cell of an Excel spreadsheet.
PLC
or SBC
Although
the T100MD-888+ and T100MD-1616+ are called PLCs, in reality
they’re more like SBCs. The capability of computing as
well as controlling outside your everyday view sets T100MD+
devices into the SBC realm. The strong Java-based TRiLOGI
software made putting the PLCs on the Internet a snap.
PLC or SBC, the ’888+ and ’1616+ aren’t complicated, they’re
embedded.
