AERCO Modbus Communications Manual for ECS - Manual (Page 5)

AC-106 INSTRUCTIONS - ECS COMMUNICATIONS
1
ELECTRONIC CONTROL SYSTEM COMMUNICATION INTERFACE
1. INTRODUCTION
The Electronic Control System (ECS), used on AERCO indirect fired water heaters, can be ordered with a
MODBUS® Communication Option, which will permit it to be controlled by an external Energy
Management System (EMS), Building Automation System (BAS), or a computer supplied by others.
2. COMMUNICATION BOARD
The Communication Board provides the MODBUS interface between any of the possible external control
systems and the ECS. The Temperature Controller (Eurotherm 2408) used in the ECS can be optionally
equipped with a Communication Board which can be connected to external control systems utilizing either
an RS232 or RS485 MODBUS communication interface. The corresponding part numbers for the
alternative MODBUS Communication Boards are as follows:
PART NUMBER DESCRIPTION
64009-1 RS232 COMMUNICATION BOARD
64009-2 RS485 COMMUNICATION BOARD
3. MODBUS COMMUNICATION SIGNAL CONNECTIONS
CAUTION
DO NOT route MODBUS communication wiring in the same conduit as power wiring.
Attempting to do so may result in excessive noise on the signal lines. Also, ensure that
the RS232 or RS485 signal cable connections do not exceed the following lengths:
CABLE TYPE
MAXIMUM LENGTH
RS232 50 feet
RS485 4,000 feet
To implement ECS MODBUS control, connect the cable leads from the external controller to the
Temperature Controller as instructed in Table 1.
• Refer to the Temperature Controller (Eurotherm 2408) pinouts shown in Figure 1 to locate the
required terminals.
• Refer to Table 2 Eurotherm Series 2400 Controller MODBUS Points for a listing of active
MODBUS data addresses for the 2408 Controller.
• The Eurotherm documents referenced on page 3 provide additional communication information
related to MODBUS.
NOTE
AERCO recommends that shielded, twisted-pair cable be used for communication wiring.
Examples of suitable wiring are: Belden 9841, 8761, 3105A, or equivalent.