Functional description

• Pin description robust trackers
  • RS232 variant
  • RS422 variant
• RTCM corrections
• Peripheral interfaces
  • CAN (Controller Area Network)
  • RS232 with RTS/CTS flow control
  • RS422
  • RTCM/SPARTN Corrections Input Port

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This chapter describes the Sirius series pinout and gives details about the supported communication interfaces.

 

Pin description robust trackers

Below figure shows the pin configuration of the Xsens Sirius series robust tracker.

 

 

Pin configuration of the Xsens Sirius series robust tracker: IMU/VRU/AHRS (left) and GNSS/INS (right)

 

Below table shows the pin descriptions of the Xsens Sirius series robust tracker based on the interface variant.

 

 

RS232 variant

 

Pin descriptions Rugged Sirius Host Interface with RS232

 

 

RS422 variant

 

Pin descriptions Rugged Sirius Host Interface with RS422

 

RTCM corrections

 

Pin descriptions Sirius RTK GNSS/INS RTCM corrections connector

 

Peripheral interfaces

The rugged Sirius series supports CAN(-FD), and RS232 or RS422 interfaces for host communication. For more detailed information on the interfaces please refer to the Sirius series Hardware Integration Manual.

 

CAN (Controller Area Network)

A Controller Area Network (CAN bus) is a robust standard designed to allow communication between devices in applications without a host computer. By default the CAN interface of the Sirius series does not have a termination resistor enabled. It can be used in a CAN bus that already incorporates the required termination. If used in a single device connection or when placed at the end of a CAN bus, the internal 120 Ω termination resistor can be enabled. 

 

RS232 with RTS/CTS flow control

The RS232 interface complies with the standard RS232 voltage levels. It includes hardware flow control (from firmware version 1.1.0 onwards) through the RTS and CTS lines. The RS232 frame configuration is 8 data bits, no parity and 1 stop bit (8N1).

 

The CTS signal is an input for the device. The device checks the state of the CTS line at the start of every byte it transmits. If CTS is high, the module transmits the byte. Otherwise, it postpones transmission until CTS is raised. When during the transmission of a byte the user lowers the CTS signal, then the device completes transmission of that byte before postponing further output. The device will not retransmit this byte. Figure 1 shows the behavior of the TX and CTS lines.

 

Figure 1: Data transmit behavior under CTS

 

The RTS signal is an output of the device. If the RTS line is low, the device is busy and unable to receive new data. Otherwise, the device’s UART is idle and ready to receive. After receiving a byte the direct memory access (DMA) controller of the device will transfer the byte to its receive first-in-first-out (FIFO) buffer. The device will pull down the RTS signal during this transfer. Therefore, with every byte received, the device lowers the RTS line shortly. Figure 2 shows this behavior.

 

Figure 2: RTS behavior during data reception

 

The user can use this communication mode without hardware flow control. In this case, the user must tie the CTS line high (e.g. VIN) to make the device transmit.

RS422

The RS422 interface complies with the standard RS422 voltage levels. It replaces the RS232 lines of the default interface. The RS422 frame configuration is 8 data bits, no parity and 1 stop bit (8N1). The RS422 interface does not support flow control.

RTCM/SPARTN Corrections Input Port

The RTCM/SPARTN input port on the Sirius RTK-GNSS/INS (product code S1R43x) can be used to provide correction messages using the RTCM or SPARTN protocol. The port uses RS232 signaling with 8 data bits, no parity and 1 stop bit. The default baud rate on this port is 38400 bit/s, but a higher baud rate can be configured. Refer to the table below for available baud rates. Setting the baud rate is possible using MT Manager or using low level commands. Please refer to the low-level communication document for details on the SetPortConfig command and how to configure it.

The input port also outputs a GGA message at a 1 Hz interval. This GGA message is often required by NTRIP providers.

 

RTCM input port baud rates