Atal AWP-C, User Manual, Page: 45 / 82

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Communication protocols
Modbus TCP
Modbus TCP protocol allows for measured values from device to the 3
rd
party
SCADA software. Modbus TCP server supports two connections (sockets)
simultaneously. Default TCP port is 502. Modbus device address (Unit
Identifier) can be arbitrary. Modbus write command is not supported. Brief
description and example in Python language is available at About / Library
section of webpages. Detail description of the Modbus protocol is free to
download at
www.modbus.org .
Supported Modbus commands (functions):
Command Code Description
Read Holding Register(s) 0x03 Reads 16-bit register(s)
Read Input Register(s) 0x04 Reads 16-bit register(s)
Table with Modbus registers. Depending on used communication library it
may to be required insert register number(s). Number of the register is an
address of register plus one (e.g. register with number 0x9C41 have the
Modbus address 0x9C40). Inside Modbus TCP frames are physically send
address.
Variable Address
[HEX] Address
[DEC] Type
Device identification
Serial number
(device serial number have 8 digits which are split
into four Modbus registers)
0x9C22 39970 BCD
0x9C23 39971 BCD
0x9C24 39972 BCD
0x9C25 39973 BCD
Device type 0x9C26 39974 HEX
Device states
Internal acoustic signalisation 0x9C27 39975 INT
Optical LED signalisation 0x9C28 39976 INT
RSSI value 0x9C29 39977 INT
Configuration error 0x9C2A 39978 INT
System alarm - measurement error 0x9C2B 39979 INT
Low voltage of RTC battery 0x9C2C 39980 INT
Measured values