Most Access Control systems share Common inputs for their Monitored Inputs including Door Position, Deadlatch, Lock Status, REX & KOM.
If this is the case with the Access Control system you’re using and you have sufficient wires at the Lock for the Monitoring outputs, you can common together at least two of the Monitored Outputs common outputs to salvage a spare wire for 3-Wire control.
Any or all of the following Commons on the Lock Outputs can be connected together: 9, 10, 14 & 16, allowing for a minimum of 6 wires to achieve individual monitoring outputs for all functions being Door Position, Deadlatch, Lock Status, REX & Key Override.
Using this scenario, a minimum of 9 wires will enable full monitoring and control of the lock in 3-wire mode.
Additional wires could also be salvaged by placing in Series several Monitoring Outputs to a single Output, such as Deadlatch and Lock Status to provide one output to the Access Control system. Door Position may also be included in the One Output scenario, saving an additional wire.
Due to their unique functions, REX and KOM outputs should remain as individual outputs.