How to Control Serial Data Communication for a Topcon Gts 300

I had trouble finding the following information to allow control of, and data output by, a Topcon GTS 302D SurveyTotal Station. I saw that lots of other folks were looking also, so I decided to post what worked for me. This probably works for other models also.


  1. I was able to use a Tripp Lite KeyScan USB-to-Serial converter so that the total station may be used with MicroSurvey Field Genius application software on a current vintage laptop, which lacks a RS 232 serial port. The information will work on a hardware serial port, if it has one, and should work with any data collector software.
  2. The key was items 1 through 5 below. That information was posted on the MicroSurvey web site by Ned Ferguson in 2006. Thank Ned for the key.
  3. 1-Instrument type: non-robotic (a parameter that you may not need)
  4. 2-Baud rate: 1200
  5. 3-Parity: even
  6. 4-Data bits: 7
  7. 5-Stop bits: 1
  8. 6-For Flow Control: “none” worked for my 302D
  9. I tested the cable continuity from the Topcon round connector to the DB 9 female connector.
  10. Looking into the end of the round male connector, with the wide clocking tab up and at the noon position, the pin directly below the tab’s right edge that I designated as pin-6. This arbitrary assignment makes the next clockwise pin, at the 2-oclock position, pin 1.
  11. Only the following three pins are connected:
  12. Round DB-9 Signal Name
  13. 3->2 TD Tx Transmit Data
  14. 2->3 RD Rx Receive Data
  15. 5->5 GND SG Signal Ground
  16. This means that the total station uses only the send and receive lines and the common ground, and hardware handshaking for flow control is NOT used.
  17. Per a mini tester (7-LEDs) connected to the DB9, the Total station is conventional Data Communication Equipment (DCE), so no null-modem is required.
  18. If you find this, I hope it helps to get your data collector talking to your Topcon. Sorry about the formatting. Anyone who knows how to make this information fit the WikiHow system feel free to reformat.
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