RID16
Wiring
Hauser
17
a0011645
Fig. 11:
Shielding and one-sided grounding of the fieldbus cable shielding
1
Supply unit
2
Distribution box (T-box)
3
Bus terminator
4
Grounding point for fieldbus cable shielding
5
Optional grounding of the field device, isolated from cable shielding.
"
Caution!
If the shielding of the cable is grounded at more than one point in systems without potential
matching, power supply frequency equalizing currents can occur that damage the bus cable or
shielding or have a serious effect on signal transmission. In such cases the shielding of the fieldbus
cable is to be grounded on only one side, i.e. it must not be connected to the ground terminal of the
housing (terminal head, field housing). The shield that is not connected should be insulated!
4.3.6
Bus termination
The start and end of each fieldbus segment are always to be terminated with a bus terminator. With
various junction boxes (non-Ex), the bus termination can be activated via a switch. If this is not the
case, a separate bus terminator must be installed. Note the following points in addition:
• In the case of a branched bus segment, the device furthest from the Fieldbus power supply
represents the end of the bus.
• If the fieldbus is extended with a repeater, then the extension must also be terminated at both
ends.
4.3.7
Further information
General information and further points on wiring can be found on www.fieldbus.org, the Web site
of the Fieldbus Foundation or in the Operating Instructions "FOUNDATION Fieldbus™ Overview"
which can also be found on the CD-ROM. (Additional sources:
→
www.endress.de
→
Download).
