4-24
888-2629-200
10/6/10
WARNING: Disconnect primary power prior to servicing.
Section 4 Theory of Operation
Maxiva ULX COFDM Series
4.4.6
Controller Area Network (CAN) Bus
The Controller Area Network or CAN bus is a high speed serial communications link
which is used between the transmitter control boards for transmission of control, status,
fault and metering information.
The CAN bus is distributed as part of the Cabinet
Bus and System Bus
. The CAN bus can operate at speeds up to 1Mbps and is designed
to operate in hostile industrial environments. The transceivers feature cross wire, loss of
ground, over voltage and over temperature protections. A CAN transceiver connected
to the CAN bus is considered a Node. There can be up to 110 nodes on the bus with a
maximum bus length of about 40 meters for 1Mbps operation.
In a CAN system, data is transmitted and received using Message Frames. Message
Frames carry data from a transmitting node to one or more receiving nodes. The
messages transmitted from any node on a CAN bus do not contain addresses of either
the transmitting node or of any intended receiving node.
Instead, the
content
of each Message Frame (e.g. ON, OFF, PS 1 Voltage, Coolant Flow
OK etc.) is labeled by an identifier that is unique throughout the network. All other
nodes on the network receive the message and each performs an acceptance test on the
identifier to determine if the message, and thus its content, is relevant to that particular
node. If the message is relevant, it will be processed; otherwise it is ignored.
The microprocessors in the MCM and PCM boards have built in CAN controllers
which connect to a CAN transceiver and becomes a node on the CAN bus. The CAN
transceiver interfaces the single ended CAN controller to the differential CAN bus for
high common mode noise immunity, as shown in Figure 4-9. The master and slave
TCUs can send and receive information over the differential CAN bus, however the
MCM card in the main TCU determines what information is sent and when it is sent for
this application.
Exciter Parallel
Control
YES
Exciter Serial
Communications
YES
Web Connectivity
NO
Table 4-10 Life Support Functionality
System Function
Description
Available in
Life Support
Mode
Summary of Contents for Maxiva ULX
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