Garmin GTR 200B, Руководство по установке

Страница: 20 / 88

190-01553-00 GTR 200/200B Installation Manual
Rev. P Page 2-6
2.7.2 CAN Bus Considerations
The CAN (controller area network) bus (Figure 2-1) is an interface format used to establish
communication between several LRUs in the G3X system. Each end of the CAN bus “backbone” must be
terminated. Each node length (distance from CAN bus backbone to each LRU) must be 0.3 meter or less
in length (keeping the node lengths as short as practicable is recommended). There is no minimum node
length.
A GTR 200/200B can be connected in a G3X system that uses a GDU 37X or GDU 46X with CAN bus or
RS232, the CAN bus is preferred.
NOTE
Use only two CAN bus terminations per installation (even if provided more than two from
associated G3X installation kits). Using less than or more than two terminations (one at
each end of the backbone) will make the CAN bus unusable or unreliable.
Figure 2-1 CAN Bus Configuration
The following items should be considered when installing/removing/replacing LRU’s on the CAN bus:
1. CAN bus node connections must be made on the connector of each LRU that connects to the CAN
bus, do not tie CAN bus nodes from individual LRUs together into a single connection point.
2. Keep all node lengths as short as practicable, and allow only one ‘lengthy’ node if possible.
NOTE
The 120 Ω termination resistors described in the preceding paragraphs are “built-in” to
the termination method shown in Figure D-2 . Do not install a separate “discrete” 120 Ω
resistor to terminate the CAN bus.
R
L
R
L
CAN Bus Backbone
CAN HI
CAN LOW
(Node #1)
LRU
(Node #2)
LRU
(Node #3)
LRU
(Node #n)
LRU
Node Length
0.3 meter max.