IMU-KVH1750 and IMU-P1750 Baud Rate Conversion

If purchased directly from KVH, an IMU-KVH1750 or IMU-P1750 IMU must be configured before it can be used with an OEM7 receiver.

The IMU-KVH1750 and IMU-P1750 natively communicate at 921,600 bps, however the maximum baud rate of the COM ports on an OEM7 receiver is 460,800 bps. Thus, IMU-KVH1750 and IMU-P1750 IMUs purchased from KVH must be modified to use 460,800 bps. Also, the MSYNC setting on the IMU-KVH1750 or IMU-P1750 must be set to EXT.

Though slower, 460,800 bps is more than adequate to transmit the data at the required 200 Hz without any impact to performance.

There are two methods to change the IMU-KVH1750 or IMU-P1750 IMU baud rate. If an OEM6 receiver is available, a command is available that will allow the receiver to change the IMU baud rate. If not, a direct RS-422 connection at 921,600 baud is required to change the IMU baud rate.

Connect Directly to the IMU

This method requires a direct connection to the IMU at 921,600 baud over RS‑422. Make sure the RS‑422 link used is capable of 921,600 baud as not all serial ports are capable of that rate.

  1. Open a command terminal at 921,600 baud via an RS-422 serial link.

    By default, the IMU will output 0.5 Hz binary messages which will help confirm you are connected properly.

  2. Issue the following commands in sequence to enter configuration mode and change the baud rate.

    =CONFIG,1

    =MSYNC,EXT

    =BAUD,460800

  3. Upon completion of these commands, power cycle the IMU to boot up in the new baud rate.

  4. Confirm the change by connecting to the IMU at 460,800 baud and verifying the incoming messages.

The new baud rate configuration is saved to the IMU NVM automatically so the process is complete and the IMU is ready for use with an OEM7 receiver.

Use an OEM6 Receiver Command

OEM6 firmware as of version OEM060631RN0000 (Dec 2016) includes the IMUCONFIGURATION command that internally configures the IMU-KVH1750 or IMU-P1750 IMU for SPAN communication. Three sets of configuration options are available, two of which allow changing the baud rate of the IMU to either 921,600 or 460,800. This provides customers upgrading to OEM7 an easy method to modify the baud rate. To change the IMU to 460800 baud, use the following procedure:

  1. Connect the IMU to an RS-422 capable OEM6 receiver communication port.

  2. Issue the following command.

    CONNECTIMU COM# IMU_KVH_1750

  3. Issue the following command.

    IMUCONFIGURATION IMU_KVH_1750 2

The IMUCONFIGURATION command can be used to configure an IMU-KVH1750 or IMU-P1750 IMU depending on the value of the Option field.

IMUCONFIGURATION IMUType [Option]

IMU Type

Option

Configuration Details

IMU_KVH_1750

0

Configure KVH options for NovAtel communication.

1

Change KVH baud rate to 921,600

2

Change KVH baud rate to 460,800