JOHNSON CONTROLS
148
FORM 150.27-NM1
ISSUE DATE: 09/30/2015
SECTION 10 – MAINTENANCE
BACNET, MODBUS AND YORKTALK 2
COMMUNICATIONS
Data can be read and in some cases modified using a
serial communication BACnet, Modbus or YorkTalk 2
network connection. This information allows commu-
nications of chiller operating parameters and external
control changes to setpoint, load limiting, and start/
stop commands.
BACnet and YorkTalk 2 RS485 networks are wired to
the + and - terminals of TB1 for port 1 communica-
tions. Modbus network connection has the option of
RS232 or RS485 connection for port 2 communica-
tions. Modbus network is wired to either TB2 or TB3
as follows:
•
RS-485: connect to TB2 - Network (-1) to TB2
(-1); Network (+1) to TB2 (+1)
•
RS-232: connect to TB3 - Network (RX) to TB3
(TXD); Network (TX) to TB3 (RXD); Network
(GND) to TB3 (GND)
Refer to Figure 40 on page 149 “Micro Panel Con-
nections” for TB1, TB2 and TB3 locations.
In most cases, communication parameters will need to
be modified.
Values Required For Bas Communica-
“Values Required for BAS Com-
munication” lists setup parameters for the available
protocols. Modification is accomplished by pressing
the PROGRAM, DOWN ARROW, DOWN ARROW,
DOWN ARROW, DOWN ARROW, and ENTER keys
in sequence. The list below shows the displays for the
values that may be modified:
DE MODIFIER ADDRESS
XXXXX
DE MODIFIER OFFSET
XX
P1 PROTOCOL
XXXXXX
P1 MANUAL MAC
ADDRESS XXX
P1 BAUD RATE
XXXXX
P1 PARITY
XXXXX
P1 STOP BITS
X
P2 PROTOCOL
XXXXXXXXXX
P2 MANUAL MAC
ADDRESS XXX
P2 BAUD RATE
XXXXX
P2 PARITY
XXXXX
P2 STOP BITS
X
P2 HW SELECT BIT
XXXXX
REAL TIME ERROR ##
RESET 1 = YES, 0 = NO 0
Note:
See Table 29 for error descriptions
