Rockwell Automation 198 Series C Modular DeviceNet Starter Auxiliary User Manual - Manual (Page 59)

Programming 4-12
Publication 198-UM002A-EN-P December 2001
Close window and begin coding for the program. An example program in which an MDSA
turns on an AC starter for 10 seconds follows.
Notice that each of the bits in the program is labeled with the same address as those mapped
to the scanner. For example, input assembly 105 shows that the first two bytes are for status,
which leaves the last six bytes for the inputs. According to what was mapped to the scanner,
the last two bytes are located at address I: 1.2, I: 1.3 and I: 1.4, which are the same addresses
used in the above program. The same can be seen for the output assembly.
The inputs and outputs can also be monitored by the use of RSLogix. To monitor an input,
select
,QSXWV under the 'DWD folder in the left panel of the screen. A data table with the
addresses of all the inputs in the system will be displayed. As you change system inputs, you
will see the bit at that particular address change. For example, when the program above is in
run mode and the Auto switch is on, bit I: 1.3/1 will change from 0 to 1. You can also
monitor the outputs in a similar fashion.
It is important to use the I/O Module Status bits for the modules on the MDSA. Use these
bits to ensure that the program only executes when these bits are zero. If these bits are ever
set to “1”, the MDSA has encountered a major fault and the data being gathered by the
scanner is invalid.