NMEA output options

If your equipment setup includes additional equipment that requires precise positions, such as ground penetrating radar or sonar systems, you can configure Trimble Access to share positions from the connected GNSS receiver as NMEA‑0183 messages.

To output NMEA‑0183 format messages and send them to the device connected to the GNSS receiver, configure the settings in the NMEA outputs screen of your GNSS survey style.

Use job coordinates

Select the Use job coordinates check box if you want the selected NMEA messages to be generated by the Trimble Access software so that they use the same coordinates and heights as the job.

If you are using a receiver with IMU tilt compensation:

  • If IMU tilt compensation is enabled and the Use job coordinates check box is selected, the software outputs pole tip (ground) positions, irrespective of whether the IMU is aligned or if the receiver is operating in GNSS‑only mode.
  • If IMU tilt compensation is enabled and the Use job coordinates check box is not selected, the receiver applies the antenna height and outputs pole tip (ground) positions.
  • If IMU tilt compensation is disabled, the receiver outputs antenna phase center (APC) positions.

For GNSS receivers that do not support tilt, heights are output as antenna phase center (APC) heights.

If you are using an R10 or R12 receiver, NMEA output during a compensated point measurement remains antenna phase center (APC) heights. There is no tilt compensation applied to positions in the NMEA messages output in either receiver or job coordinates.

Selecting the Use job coordinates check box limits the available NMEA message types to NMEA GGA, GGK, GLL and PJK messages. Clearing this check box makes more NMEA messages available for output.

Clear the Use job coordinates check box if you want the selected NMEA messages to be generated by the receiver so that they use the height reference available in the receiver. For orthometric heights this means the geoid model built into the receiver firmware is used, not the one used by the job.

Messages to output

Select the message types to output, and the rate at which each message type is output. When the Use job coordinates check box is selected, rates faster than 1s apply only to positions generated during stakeout.

Serial port settings

  1. Select the Receiver port that the additional device is using to connect to the GNSS receiver. The Trimble Access software will output NMEA messages to the same port so that they can be used by the additional device.

  2. Make sure the Baud rate and Parity settings match those set in the device that is receiving the NMEA messages.

If the controller is running Windows and the receiver supports Bluetooth, when you select Bluetooth in the Receiver port field the Trimble Access software assumes the additional device is connected using Bluetooth port 1 on the GNSS receiver. (On Windows the software always uses Bluetooth port 2 to connect to and communicate with the receiver.)

The Advanced settings group box contains configuration items that affect the format of the NMEA messages that are output.

The IEC extensions, and the setting of the GST message to GPGST rather than GLGST or GNGST at all times, are available only when using NMEA generated by the receiver firmware, where the Use job coordinates check box is not selected.

Include IEC61162‑1:2010 GNSS extensions

This setting selects which standard to use for the compliant messages. When not selected, the NMEA messages comply with NMEA‑0183 Standard for Interfacing Marine Electronic Devices, Version 4.0, November 1, 2008. When selected, the messages comply with the International Electrotechnical Commission (IEC) 61162‑1, Edition 4 2010–11.

Max. DQI=2 in GGA

When selected, the Quality Indicator field in the GGA output message is never greater than 2 (DGPS). This is to support legacy systems that do not fully support the NMEA standard.

Max. age 9s in GGA

When selected, the age of differential data field in the GGA message is never greater than 9 seconds. This is to support legacy systems that do not fully support the NMEA standard.

Extended GGA/RMC

Select this check box to output high precision position data in the NMEA messages. Clear this check box to conform to the NMEA standard message length of 82 characters. If cleared, the precision of the position and height data is reduced by truncating the number of decimal places.

GP always

When selected, the NMEA talker ID is always $GP for NMEA GST, GGA, and GLL messages regardless of the constellation(s) being tracked. For receiver firmware versions earlier than v5.10, the GP always setting applies only to the GST message type.