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Use of MTi with longer cables

The MTi series of products supports various interfaces, among which USB, CAN and serial interfaces.

In our webshop, standard length cables (approx. 3 meters) are available for basic use of the robust IP67/IP68 MTi 10-series, MTi 100-series and MTi 600-series. For the IP51 module version of the MTi 600-series it is possible to purchase a 20 cm flat ribbon cable. The module version of the MTi 600-series is designed to be embedded into system at PCB level; for long-range communications we recommend the robust version of the MTi 600-series.

Depending on the application in which the MTi product is used, these cable lengths may not be sufficient. Xsens is only able to deliver cables at the mentioned standard lengths. For custom lengths we recommend contacting the original cable/connector manufacturer or a custom cable supplier. The cable/connector brand, part number and specifications can be found in the product-specific documentation:

  • MTi 10/100-series: MTi User Manual
  • MTi 600-series: MTi 600-series Hardware Integration Manual

Considerations

The use of longer cables requires extra attention considering data throughput. The cable quality, the output configuration (data packet size and output data rate) of the MTi and the baud rate are important parameters: The cable needs to support a baud rate that is sufficient for the amount of data that needs to be transferred. With a 15 meter long medium-quality cable (~50 pF/m capacitance, conductor diameter AWG26), a 921k6 baud rate RS232 connection was successfully established. The RS422 MTi 10/100-series devices are often used on maritime vessels and other long-range industrial applications, covering up to 200 meters of cable length (link).

In addition to data throughput, these are some additional points of consideration:

  • Xsens MT Manager, the graphical user interface of the MT Software Suite, requests configuration data from the MTi, which is several hundreds of bytes. The combination of longer cables, a low baud rate and/or high data rate may block the configuration data, which can cause a time out in MT Manager. To make a connection, use USB to connect to MT Manager and set the MTi to a lower output data rate. Then connect the MTi via the long cable; the configuration data gets retrieved. Now increase the data rate. This works, since the configuration data is only retrieved from the device when first connected to MT Manager. Note that this workaround is only necessary when working with long cables.
  • The use of long cables can also lead to power supply issues. Most MTi's require a minimum supply voltage of 4.5 V, but preferably more than 5 V. As an example, a 10 meter copper cable with AWG28 conductors already results in a voltage drop of more than 10%. It is possible to apply a high voltage at the far end of the cable (near the host): Depending on the MTi model, it can support supply voltages of up to 34 V. Another option is to provide power at the MTi-side, so that the cable is only used for communication. 

Ethernet extension cables

If there are no requirements for the robustness of the cable, for instance if the cable is only used for testing, configuration or calibration purposes, then it is possible to simply extend the USB cable of the MTi or its Development Board. The typically recommended maximum cable length for USB is 5 meters. Ethernet cables can however be used over much longer distances.

Ethernet extension cables can provide a quick and easy way to cover large distances while maintaining compatibility with the MT Software Suite. Xsens has tested the Ethernet extension cables by NewLink and was able to maintain high-speed USB communication with MT Manager, Magnetic Field Mapper, MT SDK and Firmware Updater over a distance of 13 meters (incl. 3 meters of USB cable). The advertised maximum distance of 50 meters has not been evaluated and may result in power supply issues or communication timeouts, as described in the previous section.

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