Ports

The 3DM-CV7-GNSS/INS is equipped with multiple communication ports to facilitate various data transmission needs. Depending on your application and communication preferences, commands and data may be sent to the 3DM-CV7 via TTL level UART or USB. In total, the device has 5 ports: three UART ports, and 2 USB ports. Ports, and their specified protocols, are enabled and disabled with the Interface Control (0x7F, 0x02) command.

The 3DM-CV7-GNSS/INS does not have two physical USB ports. Instead, the computer that the device is connected to via USB will recognize the single connection as two separate communication ports: USB1 and USB2 (i.e. COM5, and COM6).

 

Port ID Type Name Description
0x01 Special Main Alias for USB1 (Port ID 0x21) if port is open (DTR set), otherwise serial (Port ID 0x11)
0x11 UART Uart1 “Main” serial port
0x12 UART Uart2 Serial port via GPIO 1/2
0x13 UART Uart3 Serial port via GPIO 3/4
0x21 USB Usb1 “Main” usb port
0x22 USB Usb2 "Auxiliary" usb port

The Main Port

The "Main" port refers to the main communication port that is used to send and receive data from the 3DM-CV7. When the device is connected to a computer via USB, the Main port will default to USB1. Otherwise, the Main port will be UART1. All other ports can be thought of as "Auxiliary" ports.

Auxiliary Ports

Auxiliary ports refer to any port that is not actively the Main port. Once enabled, Auxiliary ports contain all of the same functionality as the Main port. All ports, once configured with the Interface Control (0x7F, 0x02) command, have support for the protocols listed in the following table:

 

Port ID MIP RTCM SPARTN NMEA
0x01 Input/Output Input Input Input/Output
0x11 Input/Output Input Input Input/Output
0x12 Input/Output Input Input Input/Output
0x13 Input/Output Input Input Input/Output
0x21 Input/Output Input Input Input/Output
0x22 Input/Output Input Input Input/Output

 

  • MIP - MicroStrain Inertial Protocol, the main communication protocol used for all MicroStrain by HBK inertial devices.

  • RTCM - A data format used to communicate GNSS corrections from an RTK service provider to a user, commonly used for network-based RTK solutions.

  • SPARTN - A data format used to communicate GNSS corrections from an RTK service provider to a user, commonly used for PPP-RTK solutions.

  • NMEA-0183 - A standard GNSS protocol.

Input Limits

  1. MIP is always enabled on Main port (Port ID 0x01).

  2. MIP input may be enabled on up to 2 additional ports.

  3. NMEA input may be enabled on up to 1 port.

  4. RTCM input may be enabled on up to 1 port.

  5. SPARTN input may be enabled on up to 1 port.

There is no limit on output protocol quantities, but all streamed data will have the same format and decimation across ports.

Polling data always responds directly on the port that the Poll Data (0x0C, 0x0D) or Poll NMEA Data (0x0C, 0x04) command was issued, even if that output protocol isn't configured.