Rockwell Automation 2755-DM9, -DM9E High Speed Decoder - Manual (Page 21)

Chapter 3
How the Decoder Operates
3–2
MICROPROCESSOR - The microprocessor reads the information obtained
by the data acquisition circuit, processes the information, and then makes
decisions on what to do with the decoded data based upon your programming
instructions.
I/O - A single 25 pin connector (HOST PORT) provides three different
interfaces (RS-232, RS-422, and RS-485) for communications with a host
computer or programmable controller. The I/O section of the decoder
supports asynchronous data transmission at baud rates of up to 38,400 bits
per second.
Another 25 pin connector (AUX PORT) provides an RS-232 interface for
programming and monitoring of the decoder using a programming terminal.
Refer to Chapter 2 for a listing of the terminals that can be used for
programming or monitoring.
Up to eight modules can be plugged into the circuit board of the decoder.
Refer to Chapter 2 for a description of the input and output modules that can
be used. Output modules function as switches, not as power sources (refer to
Figures 3.2 and 3.3).
Note: Outputs are initially turned off (open) when power is first applied to
the decoder and when the decoder is turned off.
DC Output Module Application
Figure 3.2 illustrates a typical DC output module application. When using
high impedance loads, you may have to add an additional resistor (Rx) in
parallel with the load. Select a value for Rx that maintains a minimum
current of 10 mA through the output module in the on state. Typical values
for Rx range from 300 to 6,000 ohms depending upon the source voltage.
Figure 3.2
DC Output Module Application
DC SOURCE 3-60 VDC
_
+ _
+
Rx
DECODER
LOAD
CONNECTOR BLOCK
DC OUTPUT MODULE
FUSE