Selecting Connection Method - Mitsubishi Electric FX3U-232-BD User Manual

FX Series PLC User's Manual - Data Communication Edition
Computer Link
4.2

Selecting Connection Method

When using computer link, communication can be achieved in accordance with RS-232C or RS-485 (422).
In FX , FX , FX
3G 3GC
such a case, communication can be achieved in accordance with RS-232C on both channels, in accordance
with RS-485 on both channels, or in accordance with RS-232C on one channel and RS-485 on the other
channel.
4.2.1 For communication in accordance with RS-232C (1-to-1 connection)
With communication in accordance with RS-232C, 1-to-1 connection is applicable. Make sure that the total
extension distance is 15 m (49' 2") or less.
4.2.2 For communication in accordance with RS-485 (RS-422) (1-to-N connection)
With communication in accordance with RS-485 (RS-422), up to 16 PLCs can be connected. Make sure that
the total extension distance is 500 m (1640' 5") or less [50 m (164' 0") or less when 485BD is included].
Personal computer
FX-485PC-IF
One-pair wiring and two-pair wiring are applicable for communication in accordance with RS-485 (RS-422).
The wiring method is determined for each application. Refer to the table below, and perform suitable wiring.
*1
Computer link
: Recommended wiring method, : Applicable wiring method, —: Non-applicable wiring method
*1. When computer link is added to an existing system, adopt the wiring method used in the existing
system.
*2. For the message waiting time, refer to Subsection 6.4.3.
*3. "Echo transfer" is generated when the FX-485PC-IF is used in the one-pair wiring.
Take proper countermeasures in the computer so that the echo transfer can be ignored.
and FX PLCs, computer link is applicable in up to two channels at the same time. In
3U 3UC
Personal computer
15 m (49' 2") or less
FX PLC
Station No. 0
RS-232C/RS-485
communication
converter
+
Communication equipment
operating in accordance
with RS-485
When the message waiting time
When the message waiting time
When the on-demand function is used
FX PLC
+
Communication equipment operating
in accordance with RS-232C
FX PLC
Station No. 15
. . .
Communication equipment
operating in accordance
with RS-485
*2
should be 70 ms or less
*2
may be more than 70 ms
4 Wiring
4.2 Selecting Connection Method
+
One-pair Two-pair
wiring wiring
— 
*3 
—

D-29
A
B
C
D
E
F
G
H
I
Apx.A