GW-7552-B / GW-7552-M PROFIBUS/MODBUS GATEWAY User Manual
(Version 1.60, May/2017)
PAGE: 13
Figure 9 Configuration of pull high/low resistor for the RS-485 port
2.3.4 PROFIBUS Connection
The PROFIBUS interface of the GW-7552-B / GW-7552-M is a DB9 female
connector. The connector uses the standard Profibus 9 pin assignment. It is
recommended to use a standard PROFIBUS cable and connector (DB9 male).
As with every serial bus the rate of safe data transmission in a Profibus network
decreases with increasing distance between master and slave.
Table 7
shows the
transmission rate and range for a cable with the following properties:
1.
Impedance :135~165Ω
2.
Capacity : lower than 30 pF/m
3.
Loop resistance : lower than 110Ω/Km
4.
Wire diameter : greater than 0.65mm
5.
Core cross-section : greater than 0.34mm
2
Table 7 Transmission rate decreasing with increasing transmission distance
Transmission Rate(Kbps)
Transmission Distance per Segment (meter)
9.6; 19.2; 45.45;93.75
1200
187.5
1000
500
400
1500
200
3000; 6000; 12000
100
In order to minimize the reflection effect of signal transmission, both ends (first
node and last node) of a PROFIBUS segment needs to be equipped with an
