Selecting Connection Method - Mitsubishi FX3U-USB-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 and FX
3G, 3U
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,
*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.
PLCs, computer link is applicable in up to two channels at the same time. In such a
3UC
Personal computer
Communication equipment operating
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
: Applicable wiring method, —: Non-applicable wiring method
FX PLC
+
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.