Installation, Operating & Maintenance Instructions
Series 612 DN 63-250 (I.D. 2.5“ - 10”), RS485
VAT Vakuumventile AG, CH-9469 Haag, Switzerland
Tel +41 81 771 61 61 Fax +41 81 771 48 30 [email protected] www.vatvalve.com
289857EA
2011-07-13
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3.11.3 RS485 network topology
Note:
In the picture above, the general network topology of RS485 is shown. N nodes are connected in a multipoint RS485
network. A termination resistance is necessary on both ends of the line to eliminate reflections. Use 120
Ω
resistors (R)
on both ends. The RS485 network must be designed as one line with multiple drops, not as a star.
3.11.4 Connection cable drawing
Half duplex
Full duplex
R-
R+
T-
T+
120
Ω
R
11
24
13
12
HOST
R 120
Ω
R+
R-
T+
T-
Valve
Twisted pair
cable
Twisted pair
cable
Wiring:
T+ to R+
T- to R-
R+ to T+
R- to T-
11
Valve
24
12
13
R-
R+
T-
T+
120
Ω
R
HOST
R 120
Ω
T+
T-
R+
R-
Twisted pair
cable
Wiring:
T+ to T+
T- to T-
