Pull-up resistor on TX pin?

Hi - I’m trying to work with 2 Gamoto boards from here:http://spedr.com/2nqp2. I have the two boards connected an it seems mostly ok but there are some data glitches and I am wondering if I need the pull-up resistor as mentioned in their docs (below).

The boards share the Rx/Tx pins and have on board DIP switches to set their addresses. (The Rx/Tx are wired in parallel). Would I use just one resistor - from the MCU to the Gamoto - or two- one on each Tx line going to each Gamoto? Can I fry anything if I get it wrong?

Fwiw - this is with the Serial1 port on the Wiring board but I assume that is the same as Serial on Arduino.

tx!

–Roy

This option is normally disabled. It allows you to connect up to 8
Gamotos to the same serial TX and RX lines, with no additional
hardwareother than a 10K pull-up resistor, which may be needed in
some cases. When this bit is set, the Gamoto allows the TX line to float
when it’s not being used. Since each Gamoto only replies to messages
addressed to it (by the correct header/DIP switch combination), then
only the proper Gamoto will reply. Since the TX line is floating when not
in use, a 10K pull-up resistor is recommend, if not already
included in your serial transceiver or MCU.