Revised 4/3/00 • M220nx
4
© 2000 Automated Logic Corporation
The M220nx has an operating range of
21.6VAC to 26.4VAC. If voltage measured at
the module’s power input terminals is outside
this range, the module may not work
properly.
1. Turn the module’s power off. This
prevents the module from being powered
up before the proper voltage is verified.
2. Make sure the 24VAC power source is off.
3. Connect the power wires to the module’s
power terminals labeled Gnd and 24VAC
(see Figure 1 on page 2 for location).
4. Apply power to the transformer.
5. Make sure that 24VAC is present at the
module’s power input terminals.
6. Set the module’s address. Refer to
“Addressing” on page 3 for details about
setting the address.
7. Turn the module’s power switch on.
When the module turns on, the Run and
Power LEDs turn on. The Run LED begins
blinking and the Error LED turns off. See
Table 5 on page 8 to troubleshoot the
LEDs. If the module does not respond,
call Technical Support at (770) 429 3002.
CMnet Communications
A CMnet is a peer to peer network that allows
multiple control modules to communicate
over an EIA-485 standard. A token passing
scheme is used to control access to the
network. A CMnet may be configured as a
legacy CMnet at 9600 bps or 38.4 kbps or an
ARCNET CMnet at 156 kbps. The ARCNET
CMnet configuration provides BACnet
compatibility, as well as better performance
over a legacy CMnet. All modules on a CMnet
must communicate at the same speed.
When communicating at 156 kbps, the CMnet
uses a unique implementation of the industry
standard ARCNET protocol called ARC156.
For a summary of the differences between
ARCNET and ARC156, please refer to the
156K CMnet Wiring Technical Instructions
.
Using the M220nx on an ARC156
CMnet
Use the appropriate wire for CMnet
communications. When communicating with
the ARC156 protocol use an A3ARC156 wire
available from:
Magnum Cable Corporation
Cleveland, OH 44110-0500
(800) 421-0820
When the Comm Select jumper is set to
ARC156, the CMnet port is connected to an
ARCNET processor, enabling the M220nx to
communicate on an ARC156 CMnet.
Communication speed is 156 kbps regardless
of the Baud Select jumper setting (see below).
Using the M220nx on a 9600 or
38.4K bps CMnet
Use a dedicated 22AWG to 18AWG twisted
pair wire for legacy CMnet (EIA-485) wiring.
When the Comm Select jumper is set to
CMnet, the module communicates on a
legacy CMnet at the baud rate set by the Baud
Select jumper (see the following diagrams).
NOTE
The jumper below the Comm Select
jumper must always be set to CMnet.
CM
net
A RC156
Comm Selec t
The module communicates
on an ARCNET CMnet at
156 kbps.
C M
net
A RC156
Comm Selec t
The module communicates on
a legacy CMnet at 9600 bps.
Baud Select
9600
38.4k
CM
net
N/C
