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22 • Commercial Communicating Programmable Thermostat I&O Manual
026-1729 Rev 2 15-NOV-2016
8
Network Setup and Commissioning
8.1. COM Port Associations
- E2 Versions 3.xx and
Below
Connecting the thermostat to an E2 requires the E2
to be version 3.0 or above. Contact Emerson Retail
Solutions for upgrade information if the controller is
a version before 3.0.
An E2 has up to three COM ports that can be as-
signed for MODBUS communication: COM2, an
RS485 port on the E2 power interface board, and
COM4 and COM6, which are optional ports requiring
expansion cards.
COM ports can only be used for one function; in
other words, if COM2 is set up as the I/O network,
you cannot connect MODBUS devices to COM2. En-
sure your E2 is equipped with an RS485 COM Card
(P/N 637-4890)
and configured in E2 General Ser-
vices (
,
Serial
tab) to enable COM4 or
an E2 Expansion COM Card
(P/N 637-4871)
to en-
able COM6.
Connect the MODBUS network cable to the three-
terminal connector on the COM port you wish to as-
sign as MODBUS.
8.2. COM Port Associations
- E2 Versions 4.0 and
Above
An E2 has three COM ports that can be assigned
for MODBUS communication (COM2). COM ports
can only be used for one function; in other words, if
COM2 is set up as the I/O network, you cannot con-
nect MODBUS devices to COM2. Ensure your E2 is
configured in E2 General Services (
,
Serial
tab)
to enable COM4 or COM6.
Connect the MODBUS network cable to the three-
terminal connector on the COM port you wish to as-
sign as MODBUS. Reverse polarity of +/- on RS485
cable from E2 to the device.
Figure 8-1
- Location of E2 COM Ports (E2 versions 3.xx and
below)
E2 PIB COM PORT ASSOCIATIONS
COM1
COM4
COM6
COM2
Serial Device
RS485 COM Port
(2 Connectors)
RS485 COM Card
(2 Connectors)
Serial Device
RS232 Port
POWER INTERFACE BOARD
(PIB)
E2 Modem/Expansion
COM Card Mounted
Above PIB
Plug-In
Modem
Card
COM3
E2 Enclosure (Right Side)
RS485
RS232
Figure 8-2
- Location of E2 COM Ports - E2 PIB Board (E2
version 4.0 and above)
E2 PIB COM PORT ASSOCIATIONS
COM1
Serial Device
RS232 Port
POWER INTERFACE BOARD
(PIB)
E2 Enclosure (Right Side)
COM2
COM6
COM4
Serial Device
RS485 COM Ports
Plug-In
Modem
Card
COM3