Description
R&S
®
TS-PWA3
23
User Manual 1157.8143.12 ─ 17
In addition, the system CAN bus is available at the CAN connector on the rear I/O slot
A4.
The option R&S TS-PXB2 cannot be used together with the power backplane. The
jumpers and the assignment of the connectors in the rear I/O area are described in
Chapter 3.6, "Permitted Module Configuration"
3.3.4
Ground Concept
An electrically conductive CHA-GND (chassis GND) pad in the mounting area on the
cPCI backplane provides an impedance grounding to the chassis. Screw connections
and a busbar on the cPCI backplane are used to make a low-resistance connection for
GND and CHA-GND, while a star connection between GND and CHA-GND using a
busbar prevents unwanted ground loops.
A capacitor creates the HF connection between GND and CHA-GND at each slot. A 1
M
Ω
resistor discharges the capacitors and dissipates static.
A 3-pin connector provides the 230 VAC supply for the PSU on the control backplane
(at X0).
The optional power backplane is supplied with AC voltage parallel to the cPCI back-
plane.
The PE conductor must be bonded to the case with a grounding cable.
The GND signal of the analog bus backplane is connected by a cable and screw termi-
nal to the GND on the cPCI backplane. This prevents the large induction loops that
would occur if a return via chassis were to be used.
The ground screen of the analog bus between two basic frames is connected to CHA-
GND (chassis).
In the second frame, CHA-GND must not be connected to GND to prevent ground
loops. The connections are indicated in
.
GND sense of +5 V and +3.3 V (of the second PSU as well) are connected to GND at
the grounding star point.
Construction
