ENCARDIO RITE ESM-40S, Руководство пользователя

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Users’ Manual ESM-40S High sensitivity settlement monitoring system
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8.4 Modbus details for connection to datalogger
8.4.1 Modbus RTU overview
The Modbus RTU protocol uses packets (messages made up of multiple sections) to communicate and
transfer data between devices on the network. The general format of these packets is as follows:
1. Modbus Address (1 byte) – The address of the specific device on the bus.
2. Function Code (1 byte) – The action to be carried out by the server device.
3. Data (multi-byte) – The payload of the function code being sent.
4. Cyclic Redundancy Check or CRC (2 bytes) – A 16-bit data integrity check calculated over the other
byes in the packet.
8.4.2 Function code
The Modbus RTU protocol uses following Function codes:
Function Code Description
03 Read Holding Registers
06 Write Single Register
8.4.3 Modbus register table
Modbus tables (maps) define the memory locations within each ESM-40S sensor interface and what
information they contain. For example, the most recent sensor reading is stored in a table. This reading is
presented in different formats in different sections of the table. The register location and size of these
variables is detailed in the table below.
Modbus
Register
Name Data
Length
Data Type Description
0x00D8 Temperature Unit 2-bytes 16-bit Unsigned Integer 0 = deg C
1 = deg F
0x00D9 Parameter Unit 2-bytes 16-bit Unsigned Integer 0 = meters, 1 = mm
2= feet, 3=inches
0x00DA Average Samples 2-bytes 16-bit Unsigned Integer 1 - 255
0x00DB Settling Time 2-bytes 16-bit Unsigned Integer 0 – 255 seconds
0x00DD Address of the
Device
2-bytes 16-bit Unsigned Integer 0 - 247
0x00DE Baud Rate 4-bytes 32-bit Unsigned Integer 1200, 2400, 4800, 9600,
19200, 38400, 115200
0x00E0 Endian Type 2-bytes 16-bit Unsigned Integer 0 = Little Endian Atomic 8
1 = Little Endian Atomic 16
2= Big Endian Atomic 8
3 = Big Endian Atomic 16
0x012C Ch-1 Status 2-bytes 16-bit Unsigned Integer 0 = Measurement Ready
1 = Busy in measurement
0x012D Parameter Value 4-bytes 32-bit float 0 – 1000 mm
0x012F Ch-2 Status 2-bytes 16-bit Unsigned Integer 0 = Measurement Ready
1 = Busy in measurement
0x0130 Temperature 4-bytes 32-bit float -20 to +80 deg C