Product Overview

© Danfoss | DCS | 2019.04
Danfoss 80G270.10
T D+ D-
D-
D+
120Ω
D+ D-
120Ω
EKE
End- point
termination
Marster controller
EKE
Data sheet | Superheat controller type EKE 1A, EKE 1B, EKE 1C
DKRCC.PD.RS0.A4.02 | 25
Danfoss 80G8269.01
D
R
D
R
D
R
Slave 1 Slave 2
Master
LT LT
D+
5 V
D-
Common
Pull up
Pull down
Ballanced pair
8.0 Modbus
communication
Details about the Modbus communication can be found in “EKD / EIM Data communication MODbus
RS 485 RTU design guide”.
The brief on EKE MODbus RS – 485 RTU has been explained below.
EKE controller uses half duplex standard MODbus RTU protocol.
With the following defaults :19200 Baudrate, Even parity and one stop bit.
The default unit address is 1 which can be changed using parameter “is G001 Controller Adr”.
8.1 Modbus RTU setting
8.2 Addressing
convension
Data Feature
Controller address (G001) Range 1 - 120, default address 1
Modubs Baud Rate (G005) 1200, 2400, 4800, 9600, 14400,19200, 28800, 38400 Default value: 19200
Modbus mode, selection (G008) 8N1, 8E1, 8O1 and 8N2
There must always be two terminations on the network, one at each bus end. The termination can
be installed by connecting a 120 Ohm resistor between D+ and D- for RS-485.
Above image shows how a Modbus network is typically terminated. The resistors are picture called LT
(Line Termination) and are typically 120 Ohm.
The pull up and pull down are usually built into the master on the Modbus. They are not built in
Danfoss EKE controllers.
In EKE controllers. when addressing holding registers on Modbus. the range of valid addresses is
0-65535 (0x0000 to 0xFFFF). In this convention the range of valid register numbers is 1-65536. and
the register address 0 is referred to as register number 1.
Danfoss EKE follows this convention so when reading the PNU (Parameter Number) 117, the actual
request asks for data from Address 116. So address = PNU – 1
Note:
Default modbus setting:
19200 8E1
Note:
Modbus address = PNU – 1
EKE 1A 1B 1C
Applicable
-