Rockwell Automation 6008-SI IBM PC I/O SCNNR 6008-SI - Manual (Page 107)

Chapter 8
Block Transfer
8-17
The 1771–DCM (Direct Communication Module) is a module that plugs
into any existing 1771 chassis that has a free empty slot. It allows data to
be collected by the PC I/O scanner from an existing I/O chassis. The DCM
appears to the scanner as a rack of I/O, exactly the same as a PLC5 in
adapter mode. The scanner can scan the DCM and automatically get eight
words of discrete input data and provide eight words of output data, or the
scanner can block transfer data to the DCM. The DCM can communicate
at either 57.6K Baud or 115.2K Baud.
The local PLC, in the same rack as a DCM, block transfers data that needs
to be sent to the scanner through the DCM. Once the DCM has gotten the
data from the local PLC, it is ready to do a block transfer with the scanner.
The block transfer programming techniques are exactly the same as
communicating with a PLC5 in adapter mode.
Figure 8.2 shows a typical configuration using a DCM with your scanner.
Figure 8.2
Example Configuration of Scanner and 1771ĆDCM
P
L
C
5
D
C
M
A
S
B
Remote Rack
A
S
B
Remote Rack
1771 I/O Rack
Block Transfer to a
1771-DCM