Omron K3HB, Technical Communications User'S Manual

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1-3
Communications Method
Section 1-1
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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:
1-1-4 Cable Connections
RS-485
• 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.
Command
Response
Command
Maximum of 3 sets of
setting data can be written
50 ms or higher
B
B (+)
A (
−
)
B (+)
RS- 485
A (
−
)
A B C D E
1 1
2 2
3 3
4 4
5 5
6 6
RS-485
RS-485
At least AWG28
Conductor cross-sectional area:
0.081 mm
2
min.