Yokogawa µR20000 - Manual (Page 30)

3-2
IM 04P01B01-17E
3.2 Terminal Arrangement and Signal Names and
the Connection Procedure of the RS-422A/485
Communication Interface
Terminal Arrangement and Signal Names
L
N ALARM
CHART
REMOTE
1 2 3
RS-422A
SD SD SG A B G
RD RD FG A B G
4 5 C
NO C NC
NO C NC
NO C NC
NO C NC
NO C NC
NO C NC RS-422A
SD SD SG
A B
RD RD FG
A B
SDA SDB SG
RDA RDB FG
Rear panel
Terminal Name Description
FG (Frame Ground) Case ground of the recorder.
SG (Signal Ground) Signal ground.
SDB (Send Data B) Send data B (+).
SDA (Send Data A) Send data A (–).
RDB (Received Data B) Receive data B (+).
RDA (Received Data A) Receive data A (–).
Connection Procedure
• Cable
Use the cable that meets the conditions below.
Item Conditions
Cable Shielded twisted pair cable
3 pairs AWG24-14 (Four-wire system),
2 pairs 24 AWG or more (Two-wire system)
Characteristic impedance 100 Ω
Capacitance 50 pF/m
Cable length Up to 1.2 km*
* The transmission distance of the RS-422A/485 interface is not the straight-line distance, but
rather the total length of the (shielded twisted-pair) cable.
• Connecting the Cable
As shown in the following figure, attach a crimp-on lug with isolation sleeves for 4 mm
screws to the end of the cable. Keep the exposed section from the end of the shield
within 5 cm.
SDB SDA SG
RDB RDA FG
Electric
potential of
the shield
Shield
Four-wire system Two-wire system
SDB SDA SG
RDB RDA FG
Electric
potential of
the shield
Shield