2.2Examples of one-pair wiring (for RS-485 circuit)
(1)When connecting one computer and one PC
Cable connection and signal direction | 485ADP | Application | ||
Signal name | Signal name | |||
|
|
SDA |
| RDA | Reception data |
SDB |
| R*1 | Reception data |
| RDB | ||
RDA |
| SDA | Transmission data |
R*1 |
| SDB | Transmission data |
RDB |
| ||
LINK SG |
| LINK SG | Signal ground |
Grounding |
| FG *2 | Frame ground |
| 24V *3 | Power supply terminal | |
resistance of | DC24V | ||
100 Ω or less | FX base unit | 24G *3 | Power supply terminal |
(2)Computer and PCs in 1 : n connection ( n has a maximum value of 16 ).
The terminal lagout shown is diagrammatic only. As for 485ADP, see chapter 1, and as for
Computer
SD
RD
485ADP | ||
|
| Station |
|
| No. 0 |
| SDA | SDA |
SD | SDB | SDB |
|
| |
R*1 | RDA | RDA |
| ||
RD | RDB | RDB |
|
| |
| LINK | LINK |
| SG | SG |
|
| *2 |
|
| FG |
485ADP | 485ADP |
|
Station | Station |
|
No. 1 | No. 15 |
|
SDA | SDA |
|
SDB | SDB |
|
RDA | RDA | *1 |
|
| R |
RDB | RDB |
|
LINK | LINK |
|
SG | SG |
|
*2 | *2 |
|
FG | FG |
|
*1 R is the terminating resistance. Connect the terminating resistance (110 Ω) between terminals
RDA and RDB . For details see section 2.3.
*2 Connect terminal FG to earth terminal 
of the PC main body grounded with resistance of 100
Ωor less. However, as for the computer link unit of the A series PC, see the manual of the computer link unit.
*3 The 24V DC power requirement can be taker from the service power supply of the PC.