ABB M101, Руководство пользователя, Страница: 23 / 74

COMM UNICATION INTER FACE CO NNECTIO N SWITCHGEAR BUS NETW OR K
1TG C908004M0 201 15
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5.Communication Interface Connection
5.1. Switchgear Bus Network
The communication between MNS Digital Gateway and M10x is established via Modbus RTU
protocol.
Modbus RTU is a single master/multiple slave type of protocol which is suitable for a multi
drop wiring installation as supported by RS485 hardware. In this case, M10x-M device acts as
a Modbus slave while MNS Digital Gateway acts as a Modbus master.
RS485 is a balanced two-wire transmission and multi-drop system. RS485 supports 32 de-
vices (one master and 31 slave devices) over distance up to 1.2 km in a single segment. 120
ohm resistors are required as terminators for both end of each communication link. The MNS
Digital Gateway has an inbuilt terminating resistor on its serial port which acts as a first
point, while for the last point, one 120 ohm resistor needs to be installed
Figure 9 Hardware connection between MNS Digital Gateway and M10x
The settings required in M10x to establish the communication between M10x and MNS Digital
Gateway are the device address, baud rate, Modbus stop bit and Modbus parity check. The
following table shows the setting required for the M10x communication.
Baud Rate Stop Bit Parity Check
9600
1 Even
19200 (to be used along with
EMax ACB)
38400 (default)
57600*
*57600 Baud shall be set for max. data throughput but installation has to be handled with care and max. stub
length of communication cables have to be considered for reliable communication !
Table 5 M10x Communication setting