PROFI-25xx User Manual
Version 13
Page
：
9
Copyright © 2017 ICP DAS Co., Ltd. All Rights Reserved E-mail: [email protected]
2. Hardware
2.1 Bus Wiring
In order to minimize the reflection effect of the signal transmission, PROFIBUS device has to fit
with an active terminal resistor at both first node and last node, as shown below.
Device
1
Device
2
Device
N
……
B-Line
A-Line
VP
VP
GND
GND
390
Ω
390
Ω
390
Ω
390
Ω
220
Ω
220
Ω
However, the number of station in PROFIBUS network is also restricted. According to
PROFIBUS specification, it is up to 32 stations connected in a PROFIBUS segment. If more than
32 stations are connected, the PROFIBUS repeater must be used to link the individual bus
segments.
2.2 PROFIBUS Cable and Transmission Distance
The PROFIBUS cable with following properties has different transmission distance with respect
to different transmission rate, shown in the following table
1.
Impedance :135~165Ω
2. Capacity : lower than 30 pF/m
3.
Loop resistance : lower than 110Ω/Km
4. Wire diameter : larger than 0.65mm
5. Core cross-section : larger than 0.34mm
2
Transmission Rate(Kbps)
Transmission Distance per Segment (meter)
9.6, 19.2, 45.45, 93.75
1200
187.5
1000
