Harris ATLAS ANALOGUE, Manual

Page: 120 / 134

4-6 888-2523-001 7/26/05
WARNING: Disconnect primary power prior to servicing.
Section 4 Theory of Operation
ATLAS Analogue
the single ended CAN controller to the differential CAN bus for high common mode
noise immunity, as shown in Figure 4-2. All of the control boards can send and receive
information over the differential CAN bus, however the Main Controller determines
what information is sent and when it is sent for this application.
NOTE:
There is an LED on the Main Controller, DS24, which will flicker on and off at a
random rate indicating that there is activity on the CAN bus. If the LED is off or
always on, then the CAN bus is most likely not communicating.
Figure 4-2 CAN Transceiver Diagram
All fault reporting and status and metering information displayed on the GUI is sent on
the CAN bus to the Main Controller and to the External I/O board for remote
monitoring. Transmitter control signals are also sent via CAN but are also sent over
hardwired parallel control lines.
4.3.4 System Control Bus
The System Control Bus is a multi-conductor ribbon cable which distributes the CAN
(Controller Area Network) bus and several parallel control lines to all micro-controllers
in the system. System Control Bus connection points include:
1. Main Controller
2. Backplane Interface Board
3. PA Module Controllers (via the Backplane Interface Board)
4. RFU
5. RF Monitor Board
6. Power Block Controller Board
7. External I/O Board
1
8
7 6
5
4
3 2
Standby
Control
Reference
Voltage
Transmitter
Receiver
VREF
RXD
TXD
RS
CANH CANL
GND VCC
TXD and RXD
connect to the
CAN controller
built into the
Micro Module
(Differential CAN Bus)