Manual 2100-749
Page
60 of 68
FIGURE 82
Expansion Module (c.pCOe) Communication Wires
Modbus Troubleshooting
Use the following instructions if alarm 96, 97, 99,
101 or 103 occurs (see
Alarm Index
on page 63).
If communication to a specific device is lost, first verify
that the polarity of the wires are correct and wires are
securely connected to the specified terminal.
• For controller (PLC board) and controller expansion
(c.pCOe): The clear/white wire should land on the
positive terminal and the black wire should land on
the negative terminal (see Figures 81 and 82).
• Table 20 shows where the communication wire for
each Modbus device lands on the terminal block.
Terminals 21-26 should only have clear/white wires
landed on them and terminals 27-32 should only
have black wires landed on them (see Figure 84).
FIGURE 83
Blower/Condenser Fan Communication Wires
• For the blower(s) and condenser fan(s): The clear/
white wire should land on the RSA terminal and
the black wire should land on the RSB terminal
(See Figure 83).
Control Panel
Terminal
Modbus Device
Terminal
Modbus Device
21
FB +
Main Controller
(PLC)
27
FB –
22
J6 Tx/Rx +
Controller Expansion
(c.pCOe)
28
J6 Tx/Rx –
23
RSA
Fan 2
29
RSB
24
RSA
Blower 2
30
RSB
25
RSA
Fan 1
31
RSB
26
RSA
Blower 1
32
RSB
TABLE 20
Modbus Device Communication Wires
NOTE:
Blower terminals are not accessible while
installed in unit. To verify polarity and
communication, see
Blower Communication
Failure
on page 61.
Gen2
230V Fan
Gen3
460V Fan
FIGURE 81
PLC Communication Wires
NOTE:
Shield cables should only be landed at the
Modbus device in a specific shield terminal or
ground terminal.