Setting up the input from a motion reference unit (MRU)
The information from a motion reference unit (MRU) (normally heave, roll and pitch information) is imported into the ST90 to increase the accuracy of the echo data. The ST90 is provided with a built-in motion sensor. It is placed inside the Motor Control Unit. For improved operational accuracy, an external motion reference unit (MRU) may be used. This task is only applicable is you are using an external motion reference unit on your ST90.
Prerequisites
This procedure assumes that:
•  You have a vacant interface port on your Processor Unit.
•  You are familiar with NMEA and other relevant datagram formats.
•  You know how to set up the parameters for serial and local area network (LAN) communication.
•  The interface port is set up with the correct communication parameters.
•  The ST90 system is turned on and operates normally.
•  The new sensor is physically connected to the ST90 using a serial or network cable. It is switched on and in normal operation.
Neither tools nor instruments are required.
Context
A motion reference unit (MRU) measures the vessel’s pitch and roll movements in the sea. The information provided by the motion sensor is used by the ST90 to stabilize the beams and the echo presentation.
Note
This task is only applicable is you are using an external motion reference unit on your ST90.
Procedure
1 Connect the motion sensor system to an available communication port on your Processor Unit.
This is described in the ST90 Installation manual.
2 Open the Setup menu.
3 On the Setup menu, select Installation.
Image
Observe that the Installation dialog box opens. This dialog box contains a number of pages selected from the menu on the left side.
Note
If you want to use a serial line to interface the motion sensor, and no COM ports are available, you must first release a port on the I/O Setup page. If you choose a serial COM port to interface the motion sensor, make sure that you do not put the same COM port to other use on the I/O Setup page.
4 Release an unused serial port (COM) port.
a On the left side of the Installation dialog box, select I/O Setup.
b Observe that the available serial and network interface ports on the Processor Unit are listed.
c If you have a vacant COM port, select it, then select Remove to delete it from the list.
d At the bottom of the page, select Apply to save your settings.
e Close the Installation dialog box.
f Restart the ST90.
Restarting allows the Processor Unit to "free" the port.
g When the ST90 has started, proceed to the Motion Reference Unit page to put the communication port to use.
5 On the left side of the Installation dialog box, select Motion Reference Unit.
6 Set up the interface.
a Select the Ethernet port or serial port you want to use.
b Select which protocol (datagram sentence) you want to use.
c If you are using a serial line, define the baud rate.
7 At the bottom of the dialog box, select Apply to save your settings.
8 Continue your work in the Installation dialog box, or select OK to close it.