Phytec phyCORE-167CR, Hardware Manual

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phyCORE-167CR/167CS
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PHYTEC Meßtechnik GmbH 2002 L-527e_8
6.2 CAN Interface
The phyCORE-167CR/167CS is designed to house two
CAN transceivers at U11 and U12 (either PCA82C251 or Si9200EY).
The CAN bus transceiver devices support signal conversion of the
CAN transmit (CANTx) and receive (CANRx)lines. The
CAN transceiver supports up to 110 nodes on a single CAN bus. Data
transmission occurs with differential signals between CANH and
CANL. A Ground connection between nodes on a CAN bus is not
required, yet is recommended to better protect the network from
electromagnetic interference (EMI). In order to ensure proper
message transmission via the CAN bus, a 120 Ohm termination
resistor must be connected to each end of the CAN bus.
For larger CAN bus systems, an external opto-coupler should be
implemented to galvanically separate the CAN transceiver and the
phyCORE-167CR/167CS. This requires the CANTx and CANRx
lines to be separated from the on-board CAN transceivers by opening
Jumpers J16, J17, J18, and J19. For connection of the CANTx and
CANRx lines to an external transceiver we recommend using a
Hewlett Packard HCPL06xx or a Toshiba TLP113 HCPL06xx fast
opto-coupler. Parameters for configuring a proper CAN bus system
can be found in the DS102 norms from the CiA
1
(CAN in
Automation) User and Manufacturer’s Interest Group.
Note:
If the C167CR controller populates the phyCORE module, using the
CAN interface reduces the available address space to 1 MB for each
/CS signal.
___________________________
1
: CiA: CAN in Automation. Founded in March 1992, CiA provides technical, product and
marketing information with the aim of fostering Controller Area Network’s image and
providing a path for future developments of the CAN protocol.