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IMU User Guide revision 3.1 SMC Ship Motion Control www.shipmotion.eu
3.7
ELECTRICAL COMMUNICATION
The SMC Motion sensors are powered with a standard 12 VDC or 24 VDC supply. It is possible
however to supply power at any voltage between 10 VDC and 30 VDC. The power consumption
during normal conditions is about 2 watts for hardware versions below 8.4 and 3 watts for hardware
version 8.5 and higher.
The resistance of power cables must be so that the voltage does not drop below 12 VDC for the
motion sensor operation. The thickness of power cables is such that there is no more than a 2V drop
with a 50mA current applied over an exceptional length of cable.
The SMC Motion sensors do not have an on/off switch. The motion sensor operates as soon as power
is supplied to it. There is an initialization period that prevents the motion sensor from outputting
numerical data for the first 1 minute after the motion sensor has been powered up.
The SMC Motion sensors have both RS232 and RS422 serial outputs as standard. The motion sensor
is simultaneously communicating over both RS232 and RS422 and no configuration is needed inside
the motion sensor to activate the communications. For motion sensor firmware versions from 3.22
and higher one of the serial input ports can be used for outputting data. The baudrate and output
rate will be the same on all outputs. The string is selectable for the comport 1/2 and comport 3
separately. For firmware versions below 3.22 Only one data string output format, protocol, can be
used for both serial outputs.
Motion sensors from hardware version 8.5 are equipped with an Ethernet interface. The SMC Motion
Sensor can supply data output on both the serial and Ethernet interfaces at the same time.
In the standard delivery, the motion sensor junction box is equipped with a power cable, a motion
sensor cable and a serial DB9 cable for RS232 or RS422 communication. The Junction Box factory pre-
configuration for RS232 or RS422 can be changed in the field by modifying the wiring of the serial
cable inside the junction box. See the wiring diagram for wiring details.
The RS232 cable consists of single twisted-pair conductors, 2 wires, for full communication and a
signal ground wire. RS232 is designed for short distance communication, max 15 meters.
The RS422 cable consists of two twisted-pair conductors, 4 wires, for full communication.
The RS422 communication can achieve data transfer over long distance cables, up to 1000 meters.
The RS232 and RS422 cable normally terminates with a conventional DB9 connector.
The Ethernet cable consists of two twisted-pair conductors, 4 wires, for bi-directional
communication, following the RJ45 568B standard. The maximum cable length is approximately
100m.
Two RS232 serial ports are also available for aiding the motion sensor by GPS or Compass input.
IMU-10x with a hardware below 2.72 does not have the serial input communication ports.
Permanent damage to the motion sensor may occur if power is applied to the digital
connections. It is important to check the power connections by measuring the
voltage at the connector prior to the motion sensor being connected. Damage
resulting from incorrect connection is not covered by the warranty.
