Trebor Quantum Series Di Water Heater - Manual (Page 29)

QUANTUM DI HEATER OPERATION / MAINTENANCE MANUAL PAGE 29
4.3.c Modbus/TCP
The heater can be operated over an Ethernet network using the
Modbus/TCP protocol. Although the heater can be controlled directly
using Modbus/TCP, Trebor recommends that the heater be controlled
using a communication library written by Trebor. The Trebor
communication library abstracts the details of Modbus/TCP. Currently,
the library is available for Win32 platforms. If you need the library for
another platform please contact the factory.
The IP address of the heater can be configured from the “Config” page
on the heater touch screen (see Section 4.2.e).
4.3.d Modbus Communication
Table 1: Version 1 Modbus Mapping and Table 2: Version 2 Modbus
Mapping includes register mappings for single, dual, triple and quadruple
output Quantum heaters. For a standard single output Quantum heater
use the “Bank 1” addresses. Table 1: Version 1 Modbus Mapping and
Table 2: Version 2 Modbus Mapping contains the name, address, type,
data type, size, and read/write permission for each register.
The Table 1: Version 1 Modbus Mapping interface to the Quantum heater
is composed entirely of Modbus registers
– no Modbus coils are used.
This means that only two Modbus functions are required to communicate
with a Quantum heater. The function 03 (read holding registers) and
function 06 (write single register) are the only two Modbus functions that
will be needed.
The Table 2: Version 2 Modbus Mapping interface is an old interface that
uses both Modbus coils and registers. This interface is for backwards
compatibility with the first generation of Quantum heaters. New
installations should use the new register mapping found in Table 1:
Version 1 Modbus Mapping.
To turn the heater on remotely, the value 1 must be written to the
“Remote Heater Power” register. The heater must be in remote mode
(see Section 4.2.b) to enable remote on/off of the heater. To turn the
heater
off remotely, the value 0 must be written to the “Remote Heater
Power” register.
All of the Boolean data type registers are false when they contain the
value 0 and true when they contain any value greater than 0. When
writing to Boolean registers, false is represented by the value 0 and true
is represented by the value 1.
The float data type registers need to be converted from network format to
host format after being read. If you are using SCADA software this will
be done automatically. If you are using the C or C++ programming
languages this can be done using the C function ntohl().