Siemens LMV5 Series Technical Instructions page 37

LMV Series Technical Instructions
Document No. LV5-1000
CANbus
The CANbus is a data bus similar to a computer network. The CANbus is used to connect the actuators,
AZL5, and PLL52 module to the LMV5 base unit. Special shielded cable is used to connect all devices on
the CANbus to the LMV5 base unit. This cable carries five wires and a braided shield that is located
underneath the plastic cable sheathing.
The two heavier gauge wires (16 AWG) are used for power transmission to the connected devices. These
power wires are labeled 12VAC1 and 12VAC2, and carry 12 VAC each. These wires are powered by SEK2
Pin 1 and Pin 4 of the AGG5.210 transformer's 4-pin plug, and are fused by FU2 and FU3. These fuses
are located under black covers on the right hand side of the LMV5. If measured, 12VAC1 and 12VAC2
should have a potential of approximately 12 VAC to reference ground and 24 VAC between 12VAC1 and
12VAC2.
The two lighter gauge (24 AWG) wires are a shielded, twisted pair to help reduce noise on the line. They
carry the digital CANbus data signals and are labeled CANL and CANH. The signal on these wires consists
of 5 VDC pulses.
Note: These data wires should never contact the 12VAC wires when the system is powered. LMV5
damage may result.
The termination jumper located on each actuator and PLL52 module is used to terminate CANH and
CANL and should be moved to the bus termination position on the last CANbus device.
The last wire in the cable is the reference ground and is marked GND. This is also connected to each
device on the CANbus so that the LMV5 can monitor for voltage drops that might affect actuator
operation.
Note: It is extremely important that the shield of the CANbus cable is properly terminated.
The shield of the CANbus cable is terminated to the LMV5 by using a special strain relief (part number
AGG5.110). This strain relief also has a wire that should be connected to the shield terminal on the
LMV5, terminals X50 and X51. The installation of this clip is shown in Figure 2-1.3.
Figure 2-1.3: Installation of CANbus Strain Relief
SCC Inc. Page 3 Section 2
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