DPR-145 User Manual V-3.0
(14.09.2016)
-16-
The unit offers serial data communication port allowing it to be integrated in automation
systems.
The serial port is of RS-485 MODBUS-RTU standard. It is fully isolated from power
supply and measurement terminals for failure-free operation under harsh industrial
conditions.
The MODBUS properties of the unit are:
-Data transfer mode: RTU
-Serial data: 9600 bps, 8 bit data, no parity, 1 bit stop
-The answer to an incoming message is sent with a minimum of 4.3ms delay after
message reception.
Each register consists of 2 bytes (16 bits). Larger data structure contain multiple
registers.
Detailed description about the MODBUS protocol is found
in the document “
Modicon
Modbus Protocol
Reference Guide”
.
This document may be downloaded at:
www.modbus.org/docs/PI_MBUS_300.pdf
Supported functions:
-Function 3 (Read multiple registers)
-Function 6 (Write single register)
-Function 16 (Write multiple registers)
Error codes
Only 3 error codes are used:
01: illegal function code
02: illegal address
10: write protection (attempt to write a read_only register)
Data types
Each register consists of 16 bits (2 bytes)
If the data type is a byte, only the low byte will contain valid data. High byte is don’t care.
For data type longer than 16 bits, consecutive registers are used. The least significant
register comes first.
6. MODBUS COMMUNICATION
6.1 DESCRIPTION
