Baldor MicroFlex e100 Installation Manual - 5.6 Can Interface
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Input / Output 5-19
MN1942
5.6 CAN interface
The CAN bus is a serial based network originally developed for automotive applications, but now
used for a wide range of industrial applications. It offers low-cost serial communications with
very high reliability in an industrial environment; the probability of an undetected error is
4.7x10
-11
. It is optimized for the transmission of small data packets and therefore offers fast
update of I/O devices (peripheral devices) connected to the bus.
The CAN protocol only defines the physical attributes of the network, i.e. the electrical,
mechanical, functional and procedural parameters of the physical connection between devices.
The higher level network functionality on MicroFlex e100 is defined by the CANopen protocol,
one of the most used standards for machine control.
5.6.1 CAN connector
Location CAN
Mating connector: 9-pin female D-type
Pin Name
Description
1 -
(NC)
2 CAN-
CAN channel negative
3 CAN GND Ground/earth reference for CAN signals
4 -
(NC)
5 Shield
Shield connection
6 CAN GND Ground/earth reference for CAN signals
7 CAN+
CAN channel positive
8 -
(NC)
9 CAN V+
CAN power V+ (12-24 V)
5.6.2 CAN wiring
A very low error bit rate over CAN can only be achieved with a suitable wiring scheme, so the
following points should be observed:
H
The two-wire data bus line may be routed parallel, twisted and/or shielded, depending on
EMC requirements.
Baldor recommend a twisted pair cable with the shield/screen
connected to the connector backshell, in order to reduce RF emissions and provide immunity
to conducted interference.
H
The bus must be terminated at both ends only (not at intermediate points) with resistors of a
nominal value of 120 Ω. This is to reduce reflections of the electrical signals on the bus,
which helps a node to interpret the bus voltage levels correctly. If the MicroFlex e100 is at
the end of the network then ensure that a 120 Ω resistor is fitted (normally inside the D-type
connector).
H
All cables and connectors should have a nominal impedance of 120 Ω. Cables should have
a length related resistance of 70 mΩ/m and a nominal line delay of 5 ns/m.
1
5
6
9