User Manual
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37
Fig. 36
Modbus slaves and datapoints configuration
Table 18
Modbus RTU poll configuration
Parameter Item
Description
Device name
The Modbus slave device identifier, which is unique for the current gateway. The device name must be
less than 30 characters in length, and can contain letters, digits, underscores (_).
COM Port
Which serial port the modbus slave device connected to. Select an option from the drop-down list.
Slave address
Slave ID. Each slave in a network is assigned a unique identifier ranging from 1 to 255. When the
master requests data from a slave, the first byte it sends is the Slave ID. When set to 0, the slave will
respond to requests addressed to any ID.
Polling interval
The interval at which data is collected. Modbus is a communications protocol with half-duplex
transmission. Gateways send requests to collect data from devices. Therefore, you must specify the
data collection interval. The unit is millisecond.
If 60 milliseconds is required to collect the data of each property, the total time required to collect the
data of all properties is calculated as follows:
Total required time = Time required to collect the data of each property (60 ms) × Number of
properties for the slave device.
Modbus address mapping
This function is usually combined with register mapping to realize a single modbus command query in
data query.
Merger collection
This function is used when the register address of many data points are sequential
Table 19
Data point(node) configuration
Parameter Item
Description
Data point name
Identifier of the data point, which must be unique for the gateway. The name must be 1 to 30
characters in length and can contain letters, digits, and underscores (_).
Modbus function code
The Modbus RTU master supports the following Modbus functions: 1 Read Coils, 2 Read Discrete
Inputs,3 Read Multiple Holding Registers, 4 Read Input Registers.
