Instructions
ECL Comfort 210 / 310, communication description
4.1
RS-485 network description
The network used for this module is conditionally compliant
(implementation class = basic) with the Modbus over serial
line two-wire RS-485 interface. The module uses the RTU
transmission mode. Devices are connected directly to the
network, i.e. daisy chained. The network uses line polarization
and line termination at both ends.
These guidelines depend on the environmental conditions
and the physical network characteristics:
Maximum cable length of 1200 m without repeater
32 devices pr. master / repeater (a repeater counts as a
device)
All devices in the network must use the same communication
settings, i.e. multiple communication settings are not allowed.
The module can operate with
19200 or 38400 (default) baud rate
1 start bit
8 data bits
even parity
1 stop bit
(in total 11 bits).
For specific details, please consult the specifications
Modbus Application Protocol V1.1a.
Modbus over Serial Line, Specification & Implementation
guide V1.0
both of which can be found on
http://www.Modbus.org/
4.1.1 Network layouts
Figure 4-2 illustrates how termination and line polarization
must be added. For specific details, consult the Modbus
specifications.
M
LP
T
T
M
LP
T
R
Master (PC)
Line Polarization
Terminator
Repeater
M
R
R
LP
T
T
T
T
T
LP
T
T
LP
T
LP
M
LP
T
T
Figure 4-2: Three daisy chain network layouts
Danfoss District Energy
VI.LG.V3.02
DEN-SMT/DK
6
