EKO MS-80 - Page 57

EKO INSTRUMENTS CO., LTD. - Pyranometer MS-80/80S/80U - Instruction Manual Ver. 1
Pg. 56
A-4. Communicati on Speci ficati ons (Mod bus RTU )
A4-1. Outlines
・ This device is compatible with Modbus RTU*. ASCII modes are not supported.
(* This is an open protocol for serial communication developed by Modicon.)
・ The initial setting of the communication interface is Modbus mode. To use the SDI-12 mode, change the
settings from “Hibi” software. After changing the setting, turn the power off and then on again to operate
with SDI-12. To return to Modbus mode again, change the setting from “Hibi” software.
・ It corresponds to RS485, half-duplex and double-wire multi-drop networks.
The communication specifications are as follows.
Table A4-1. Modbus communication protocol
Optional item Remarks
Electrical specifications EIA-485
Connection form Multi-drop method (1 for Master, 31 for Slave, 32 for total)
Communications protocols
Modbus RTU
※
1 (Slave)
Communication speed baudrate
2400
、
4800
、
9600
、
19200
、
38400
、
115200 bps
Data length
8 Bit
Stop bit
1 bit/2 bit ※2
Parity bit
None/Odd/ Even
Communication distance
Max.1000m (ideal value)
Error detecting system
CRC-16
※1: An open protocol developed by Modicon for serial communication.
※2: The value of the stop bit is determined automatically by the parity bit setting.
A4-2. Function code
・ There is no distinction between Coil and Discrete Input addresses.
・ There is no distinction between Holding Register and Input Register addresses.
・ Coil, Discrete Input, Holding Register, Input Register addresses start from “0”.
Table A4-2. Supported Function Codes
Function code (hexadecimal) Function
0x01 Read Coils
0x02 Read Discrete Inputs
0x03 Read Holding Registers
0x04 Read Input Register
0x05 Write Single Coil
0x06 Write Single Register
0x10 Write Multiple Registers