Omron K3HB - MANUAL 2 Manual page 24

Communications Method
1-1-4 Cable Connections
RS-485
A B
1
RS-485
2
3
RS-485
4
5
6
The exchange between the command frame and response frame is explained
below.
After a receiving a response from the Digital Indicator, have the host computer
wait at least 50 ms before sending the next command.
When writing multiple sets of setting data in a row, such as when writing to the
variable area or performing a compound write, controllability may be affected.
Pay attention to the following points:
Maximum of 3 sets of
setting data can be written
C D E
1
2
3
4
5
6
• Use terminals B1 through B4 to communicate with the host. The terminal
layout is designed for cross-over wiring and thus the B1-B3 and B2-B4
terminals are connected internally.
• Wiring is configured either 1:1 or 1:N. A maximum of 32 Units, including
the host computer can be connected with a 1:N configuration.
• The maximum total cable length is 500 m.
• Use shielded, twisted-pair wires of at least AWG28 to AWG16 for all
cables.
Cable Diagram (Reference)
• Attach a terminator to each end of the transmission path, including the
host computer. Use a 100- to 125- Ω (1/2 W) resistor for the terminator.
• Use an RS-232C/RS-485 Converter to connect RS-232C devices, such
as personal computers.
50 ms or higher
B
B (+)
A (−)
RS- 485
B (+)
A (−)
At least AWG28
Conductor cross-sectional area:
2
0.081 mm min.
Section 1-1
1-3