Rockwell Automation SC300E Trusted Bridge Module - Manual (Page 8)

Trusted™ Bridge Module 8161
Issue 2 Feb 10 PD-8161 8
1.2 Power Distribution
Each of the Bridge modules is powered from dual redundant 5.4V dc via the backplane from the
chassis PAC or PDC dual power supplies.
1.3 Communication Busses
1.3.1 The Trusted™ to SC300E Primary Chassis
Communication between the Trusted™ Expander Interface Module and the SC300E Primary Chassis
is via one of a possible four or seven triplicated two-way interface cables. A single backplane
connector card routes the individual links in the cable to the three Bridge modules. Data voting is
provided at the Expander Module Interface to ensure that cable faults are detected.
The link handles the following triplicated signals:
Data - Serial bi-directional bus.
Control - Bus clocks, module-enables and bus direction control.
Slot - Indicating the SC300E I/O slot position to the Bridge.
Expander Chassis ID - 4 bit Trusted™ chassis address code.
1.3.2 Inter-Module Link (IML)
When returning data for Trusted™ Read requests, I/O Module data received by each Bridge module is
shared with the other two using the serial IML via the backplane. The three sets of data are then
arranged sequentially into the response packet for Trusted™. The IML is not used during Write
requests.
1.4 Function
When an I/O access is to be performed, the Trusted™ TMR Processor issues a command packet to
an Expander Interface module. The Expander Interface decodes the chassis address and transmits
the packet through the Expander bus to receivers in the 8161 Bridge modules.
For short distances of a few metres, a twisted-pair copper cable is used, whilst on longer runs the
copper cable is connected to three T8312 fibre optic units at each end of three pairs (Tx and Rx) of
fibre optic cable. The Bridge modules, receiving the command signals, decode the packet.
The Bridge modules then implement the read or write access on the SC300E I/O module selected and
return a response packet via the Expander Bus. The packet will contain both data and diagnostic
information.