SFAR-1M-4DI User Manual
Version 3.0
www.gc5.pl
Page 7 / 13
3.2.
Network termination
Transmission line effects often represent the problem of data communication networks.
These problems include reflections and signal attenuation.
To eliminate the presence of reflections at the end of the cable, the cable must be terminated
at both ends with a resistor across the line equal to its characteristic impedance. Both ends
must be terminated since the direction of propagation is bi-directional. In the case of RS485
twisted pair cable this termination is typically 120
Ω.
3.3.
Types of Modbus Registers
There are 4 types of variables available in the module
Type
Beginning
address
Variable
Access
Modbus
Command
1
00001
Digital Outputs
Bit
Read & Write
1, 5, 15
2
10001
Digital Inputs
Bit
Read
2
3
30001
Input Registers
Registered
Read
3
4
40001
Output Registers
Registered
Read & Write
4, 6, 16
Table 2 - Types of variables
3.4.
Communication settings
The data stored in the module
’
s memory is given in the 16-bit registers. the access to
registers happens via Modbus RTU or Modbus ASCII.
3.4.1.
Default settings
Parameter name
Value
Address
1
Baud rate
19200
Parity
No
Data bits
8
Stop bits
1
Reply Delay [ms]
0
Modbus Type
RTU
Table 3 - Default settings
