Greetings,
I just received the 735XT and use it for trail running but I alos use the Concept2 Indoor Rower. It seems taht I can get my heart rate to sync with the rower or my Android but I am not having much luck. The ErgData APP on my Android device will see the 735 and actually says "connected" but then the connection is gone. The settings on the 735 are to broadcast the heart rate. I have also tried Bluetooth connection but to no avail.
As for the rower, I have tried to connect to that too. There is a setting for accepting ANT+ devices and even some of the Garmin watches are listed, but not the 735. The Concept2 web site lists the 735 as one of the devices to connect.
This link shows connection for the FR60, FR70, FR210, FR310XT, FR610, FR910
http://www.concept2.com/service/heart-rate-equipment/garmin-and-suunto/how-to-use/pairing-your-garmin-watch-your-pm4
There is a reference though that shows 86 different compatible devices of which the 735 is one.
https://www.thisisant.com/directory/model-d-with-pm4/
Thank you for your thoughts in advance.
Sal