Modbus Address Filtering; Modbus Tcp Protocol Data Frame Description; Modbus Rtu Protocol Data Frame Description; Active Upload - Ebyte ME31-XAXX0600 User Manual

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4.2.2 Modbus address filtering

This function can be used in certain host software or configuration screens as the host to access the device
serial port, and the gateway function of the device is used. When the slave is on the network side and the Modbus
TCP to RTU function is enabled, the presence of multiple slaves on the bus may cause data confusion. At this time,
enabling address filtering can ensure that only the specified address can pass through the device; When the
parameter is 0, data is transmitted through, and when the parameter is 1-255, data is only transmitted through the
set slave address.

4.2.3 Modbus TCP protocol data frame description

TCP frame format：
Transaction ID
2 Bit
 Transaction identification: It can be understood as the serial number of the message. Generally, 1 is added
after each communication to distinguish different communication data messages.
 Protocol identifier: 00 00 means Modbus TCP protocol.
 Length: Indicates the next data length, in bytes.
For example：get DI state
01 00
Transaction ID

4.2.4 Modbus RTU protocol data frame description

RTU frame format：
Device Address
1 Bit
For example：get DI state command
01
Device Modbus address

4.3 Active upload

The device supports the function of uploading analog input values at fixed time intervals. Setting the value of
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15
Protocol ID Length
2 Bit N+2 Bit
00 00 00 06
Protocol ID Length
Function Code
1 Bit
02
Function Code
Device Address Function Code
1 Bit 1 Bit
01
Device Address Function Code
Data Segment
N Bit
00 00 00 04
Data Segment
ME31-XAXX0600_UserManual_CN
Data Segment
N Bit
02 00 00 00 04
Data Segment
Check code CRC
2 Bit
79 C9
CRC check code