Hi,
Yeah, your tranceiver chips doesn't have a way to disable their drivers.
When two or more of those are connected to the same pair of wires they will fight each other. I think you want the MAX3080 - not 3081 - then take your TxLED signal and wire it to the DE-pin (HIGH to enable the driver) so that ONLY the board which is actually going to put data on the bus has its driver enabled, all other boards should have their drivers disabled.

/Henrik.