Leica GRX1200 GG Pro

• GNSS - 72 Channel Tracking
  • GPS: 14L1 + 14L2
  • GLN: 12L1 + 12L2
  • SBAS: 2
• I/O
  • 4x RS-232 LEMO-1 8pin
  • Antenna: TNC
  • PPS out: ERN.0S.250.CTL
  • Event Input: HGP.00.250.CTL
  • External Frequency Input: 1x 24QMA-50-2-3/133, 5/10 Mhz
  • 10Mbit RJ-45 ethernet
  • CF card
• Power
  • 10.5-28v DC in via LEMO-1 5pin, 3.6w nominal
  • Battery: GEB171: 8Ah/12v NiMh or GEB221: 3.8Ah/7.2v Li-ion

The five-pin LEMO power supply I have did not fit the GRX1200. However the pin sockets of the GRX1200's DC in connector are just slightly larger than 0.1“, Dupont-style header pins will slightly fit. Adding a ~10º bend to the pins provides enough deflection and springiness to hold the pin in place. The top-center pin is +V, and the #3 pin, working around right to left, is ground. The ground pin is common to the ground on the RF connector, so it's easy to verify. Pin #4, to the right of the ground pin, is also a suitable DC input pin. The unit boots as soon as suitable power is applied, first the power LED is red for a couple of seconds, then green, then MEM is green (and the CF access LED blinks). Track will start to blink when it sees at least one SV, and be steady when it has a lock. Per the manual the unit can be powered off by holding down the on/off button for 4 seconds, but this does not work on my unit. Perhaps the ribbon cable is not fully re-seated after disassembly? I'll check this again later.

This unit was delivered with system firmware 8.51, and it achieved a GNSS lock within about a minute of its first power-up. It had an unknown static IP address. The CF card is a 2GB SanDisk Extreme, almost certainly not an OEM card, which would have been Leica branded. The earliest files on the card date from around 2010, and the latest - DBX * m00 hourly observation log files - are from April 2018. New files were created in the DBX directory (not *.m00 observations, though) with the current date and time. It's not yet clear if this date and time was saved by a local RTC, or if it's derived from the GNSS.

I created a blank 'GetConfig.ini' file in the \SYSTEM\ directory of the CF card (FAT16 formatted), and booted the unit with the card in place. When the CF access LED stopped blinking, I pulled the card and connected it to a computer to read out the configuration. I renamed the file to `SetConfig.ini` after changing the static IP address, and was then able to verify access over the network via FTP (username `Admin` password `12345678` - defaults). The WebUI was not installed.

I downloaded the webUI zip from Leica MyWorld, but upon installing it found that it seems to expect a 9.x system firmware - or maybe a GRX1200+, since the error on the web page references BeiDou, which as far as I know the GRX1200 GG Pro does not support. I am currently looking for an 8.x version of the webUI installer.

The GRX1200 is assembled with a number of hex screws, between 2.5 and 3mm. I actually found that a Torx T8 fit and worked the best. The only screws that need to be removed for disassembly are those around the front plate, no other external screws need to be removed. None of the connectors need to be removed. Once all the screws have been removed, the front plate can be worked free from the main housing, which it slides directly into. Pull the front about an inch forward and disconnect the power button cable, then pull it all the way out (slowly) and disconnect the ribbon cable that runs to the gold spring contacts for the RX12xx controller interface.

A central black plastic frame - seemingly glass fiber reinforced nylon or polycarbonate - is attached to the front panel. The battery cavities (or battery + ethernet in the case of the Pro models) take up a significant amount of space behind the front panel. The PCBs are attached to this frame.

• GRX1200 Technical Datasheet
• GRX1200 Getting Started
• GPS1200 User Guide v5.50
• GRX1200 Technical Reference v5.50
• GRX1200 Equipment List