Unipulse F320, Operation Manual

Page: 87 / 129

9.RS-485 INTERFACE (Communication protocol; Modbus-RTU)
73
9-2. Connecting RS-485
9-2-1. One-to-one Connection
• For connection, use twisted pair cables. (The noise margin will rise.) However,
a parallel two-core cable is good enough for short-distance connection.
• On the F320 side, mount the attached terminating resistance.
•
The terminal SG (the terminal B6) is a grand terminal used on the circuit for protecting
the circuit.When the main body of F320 and the device connected to F320
are
grounded by D type ground, there is usually no need to use the terminal SG.
However, confirm the specifications of the devise connected before connecting
the terminal SG, when it is necessary to connect it according to the situation of
the site.
9-2-2. Multiple Connection
A
B
A
B
A
B
A
B
F320
PLC/programmable
display, etc.
Terminating
(Master) (Slave)
* Logic
• Mark state (OFF)
V
A
-V
B
<-0.2V
• Space state (ON)
V
A
-V
B
>0.2V
V
A
: Voltage of terminal A
V
B
: Voltage of terminal B
Terminating
(accessory)
resistance
resistance
On some master devices, A and B may be indicated reversely. If
communications are unsuccessful, interchange A and B.
Request
A
B
A B A B
A B A B
Twisted pair cables
F320 F320 F320 F320
Terminating
Terminating resistance
resistance