Lumel RE15, Руководство пользователя, Страница: 4 / 28

4
1. PREFACE
The RE15 microprocessor controller destined to measure and
control physical quantities is provided with a serial interface in
RS-485 standard for the communication with other devices.
The asynchronous communication MODBUS protocol has been
implemented on this serial interface.
The configuration of serial interface parameters has been
described in the User’s Manual of the R15 controller.
Composition of serial interface parameters concerning RE15
controller:
•
Controller address - 1 ... 247
•
Baud rate - 2400, 4800, 9600 bits/s,
•
Working modes - ASCII, RTU,
•
Information unit - ASCII: 8N1, 7E1, 7O1;
and RTU: 8N2, 8E1, 8O1,8N1
•
Maximal turnaround time - 1s
Explanation of some abreviations:
ASCII = American Standard Code
for Information Interchange
RTU = Remote terminal Unit
LRC = Longitudinal Redundancy Check
CRC = Cyclic Redundancy Check
CR = Carriage Return
LF = Line Feed (Character)
MSB = Most Significant Bit
Checksum = Control Sum
2. DESCRIPTION OF THE MODBUS PROTOCOL
The MODBUS interface is a standard adopted by manufacturers of
industrial controllers for an asynchronous character exchange of
information between different devices of measuring and control
systems. It has such features as: