User`s manual

Western Reserve Controls WRC-CANR-DF-DN User’s Manual
PUB 14.2 Series 4
10
Table 4-6 Network Maximum Lengths - DeviceNet
Trunk Line Length Drop Length
Maximum Distance Maximum CumulativeBaud Rate
Meters Feet Meters Feet Meters Feet
125 Kbits/s 500 m 1640 ft 6 m 20 ft 156 m 512 ft.
250 Kbits/s 250 m 820 ft 6 m 20 ft 78 m 256 ft.
500 Kbits/s 100 m 328 ft 6 m 20 ft 39 m 128 ft.
DeviceNet has a limit of 64 nodes per network for any baud rate.
Table 4-7 Network Maximum Lengths - SDS
Trunk Line Length
(maximum)
Drop Length
(maximum)
Baud Rate
Meters Feet Meters Feet
No. of
Nodes
125 Kbits/s 457.2 1500 3.6 12 64
250 Kbits/s 182.8 600 1.8 6 64
500 Kbits/s 91.4 300 0.9 3 64
1 Mbits/s 22.8 75 0.3 1 32
SDS has a limit of 32 nodes per network for any baud rate.
Note:
The CANR-DF CAN bus extender does not enable the user to add more nodes. In addition,
it is transparent to the network and does not count as an addressed device.
4.5.2. Network Termination
A CAN-Bus system
must be terminated at each end of a copper trunk line
. The host
controller and the
last
node device or WRC CAN-Bus Extender on the network must always be terminated
to match impedance and eliminate reflections, even if only two nodes are present. Follow the information
below when using a CANR-DF.
The CANR Series 4 has a built-in terminator, which can be selectively included or omitted from
the network. To include the on-board terminator (on the DeviceNet side), install jumper W1; or remove the
W1 jumper if the on-board terminator in not desired. The CANR is shipped from the factory with the
jumper installed. See Figure 4-1 for the location of the jumper.
Trunk line use:
For the purpose of network termination, the CANR-DF is treated as the last node on the copper
section of the trunk network (side A) to which it is connected. Therefore, when a CANR-DF is used directly
in a trunk line, it must be terminated on side A. The terminating resistor built into the CANR-DF at W1
must be installed, or another terminator at the end of the line could be used in the place of the W1
terminator.
Drop line use:
When CANR-DF is used in a drop line (the Network A side is toward the main trunk), the Network
A connection must
not be terminated
. The user must remove the built-in terminator by removing the
jumper plug at W1.