Siemens SIMATIC NET PROFIBUS manual Ways of Installing and Grounding the Bus Terminal

Passive Components for RS-485 Networks

4.7.5Grounding

If the bus terminal is mounted on a DIN rail (see Figure 4-33), the shield clamp makes large-area contact with the rail via an internal spring. To connect the cable shield with local ground, a connection between the DIN rail over as short a distance as possible to local earth is adequate.

Installation on closet panel	Wall installation with securing	Installation with a standard rail
with securing screws	screws	on a cabinet panel

MADE IN GERMANY

Bus terminated

PEPE

A B A B

2

)

1)

Shield clamp/ grounding bar

MADE IN GERMANY MADE IN GERMANY MADE IN GERMANY

Bus				Bus				Bus
				terminated				terminated
terminated
	PE		PE		PE		PE		P		P
		A B A B							E		E
						A B A B				A B A B

Shield clamp/

grounding bar

1)If this grounding cable exceeds a length of 20 cm, the shield must be grounded to the closet panel (2).

Figure 4-33 Ways of Installing and Grounding the Bus Terminal

Note

The grounding bar and local ground must be connected by a Cu conductor with ≥ 6 mm2 cross-section over as short a distance as possible.

4-58	PROFIBUS Networks SIMATIC NET
	6GK1970-5CA20-0AA1 Release 2 05/2000