I recently acquired 4 Hanhart stopwatches. Each has external terminal connectors to sync them together. Is there anything special I need for this to work?

Problem resolved. I actually had a bad toggle switch. Once I replaced that piece, everything is fine

Syncing HANHART DELTA E 100 to time of day.

1) Press red mode button to bring up "time" in center lcd

2) Press blue set button to bring up flashing TOD

3) Increment times up with split lap button

4) Move to next time with blue set button

5) Sync TOD by pressing red Mode button (sync all watches together)

6) Time of day is now running in the upper display

7) Press split lap and start stop buttons together

8) The lower display will now show the minutes of the TOD rounded up to the next minute.

9) Press start button when TOD reaches the preset time. Both the upper and lower displays running seconds should match.

10) Press the SPlit Lap button to record splits. The times will stay frozen and be overwritten as new ones occur.

11) Pressing the mode button and the stop button together resets the splits but not the TOD