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Use of MTi with longer cables

The MTi comes standard with a dual interface, RS232 and USB. The MTi starts up with RS232 communication but when USB is detected, the MTi switches to USB interfacing. 

Longer cables may require extra attention. Much depends on the cable specification, the output configuration (data IDs and output data rate) and baud rate. With a 15 meter long medium-quality cable (~50 pF/m capacitance, conductor diameter AWG26), a 921k6 baud rate RS232 connection was successfully established. There are some points of consideration though:

 

  • Xsens MT Manager, the high-level application in the MT Software Suite, requests configuration data from the MTi, which is several 100 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 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 work around is only needed with longer cables.
  • Longer cables can be a problem, when voltage needs to be applied to the MTi via that cable. The MTi's require >4.5V, but preferably >5V. A 10 meter copper cable with AWG28 conductors 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): the MTi accepts voltages of 4.5-34V. Another possibility is to provide voltage at the MTi-side, so that the cable is only used for communication. 
  • In case RS232 is not possible after all, Xsens has a limited number of configurations available with RS422 and/or RS485 communication. See shop.xsens.com for all available configurations. 

 

 

 

 

 

 

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