Cable Lengths
The cabling characteristics and desired bit transmission rates affect the allowable
cable length. You can find detailed cable length recommendations in the ISO 11898,
CiA DS 102, and DeviceNet specifications.
ISO 11898 specifies 40 m total cable length with a maximum stub length of 0.3 m for
a bit rate of 1 Mb/s. The ISO 11898 specification says that significantly longer cable
lengths may be allowed at lower bit rates, but you should analyze each node for
signal integrity problems.
Number of CAN Nodes
The maximum number of nodes depends on the electrical characteristics of the
nodes on the network. If all nodes meet the ISO 11898 requirements, you can
connect at least 30 nodes to the bus. You can connect higher numbers of nodes if
the nodes’ electrical characteristics do not degrade signal quality below ISO 11898
signal level specifications.
The NI-9881 electrical characteristics allow at least 110 CAN ports on a network.
NI-9881 Hardware Overview
The NI-9881 has one full-featured CAN port that is isolated from the other modules
in the system. The port has a Bosch DCAN CAN controller that is CAN 2.0B-
compatible and fully supports both 11-bit and 29-bit identifiers. The port also has
an NXP PCA82C251T High-Speed CAN transceiver that is fully compatible with the
ISO 11898 standard and supports baud rates up to 1 Mbps.
Figure 4. NI-9881 Hardware Overview
NI-9881 Specifications
The following specifications are typical for the range -40 °C to 70 °C unless otherwise
noted.
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NI-9881 Getting Started
Содержание NI-9881
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