Technical data
Active components
4.1 Active components for RS485 networks
PROFIBUS Network Manual
System Manual, Edition 04/2009, C79000-G8976-C124-03
77
4.1.1.6 Connecting the bus cable
All the bus cables described in Chapter 4 are suitable for connection to the RS485 repeater.
Connecting the PROFIBUS cable
Connect the PROFIBUS cable to the RS485 repeater, as follows:
● Cut the PROFIBUS cable to the required length.
● Strip the insulation from the PROFIBUS cable as shown the figure.
The braid shield must be folded back on to the cable. Only then can the shield clamp serve
as strain relief and as the shield contact.
6,(0(16
6,(0(16
HJXQGHUJURXQGFDEOH
;9)+
HJVWDQGDUGFDEOH
;9(+
)ROGEUDLGVKLHOGEDFNRYHU
RXWHUMDFNHW
Figure 4-10 Stripping length for connecting to the RS-485 repeater
● Connect the PROFIBUS cable to the RS-485 repeater:
Connect the same wires (green/red for the PROFIBUS cable) to the same terminal A or B
(in other words always connect terminal A with a green wire and terminal B with a red
wire or vice versa).
● Tighten the shield clamps so that the shield makes good contact with the clamp.
4.1.2 Diagnostics repeater for PROFIBUS DP
What is a diagnostic repeater?
A diagnostic repeater is a repeater capable of monitoring the segment of an RS-485
PROFIBUS subnet (copper cable) during normal operation and report line faults in a
diagnostic frame to the DP master. Using STEP 7, COM PROFIBUS and with HMI devices
(SIMATIC HMI), the location of the problem and the cause can be displayed in plain
language.
The diagnostic repeater allows cable faults to be detected, located and visualized early by
means of cable diagnostics during normal operation. This means that problems in the
system can be detected in good time and downtimes minimized.