Add 2-Wire Decoder Irrigation to Your SCADA PLC

By Tony Ware on 20th May 2021

PLC (Programmable Logic Controllers) may now be enabled to run irrigation using 2wire decoders. This is useful where the PLC is already doing control, like waste-water or pumping, but irrigation or water spreading is also needed. With Irrigation added, it can then be incorporated into SCADA.

Currently, to control irrigation, multi-wire outputs (usually relay) need to be added to the PLC, with a pair of wires to each 24VAC solenoid in the valve. This is an expensive option. Now a single pair of wires with a ‘decoder’ connected to each solenoid will do the same thing. A serial output (RS232) or a Modbus RTU port (RS485) from the PLC is all that is needed to connect to the TWL BT2. This then acts as a gateway to the decoders. Up to 127 decoders may co-exist on the same 2wire path.

No protective grounding is needed along the 2wire path, just one next to the BT2. TWL’s decoders are warranted for 5 years including damage from lightning.

For more information, please contact Tony Ware:  +44 7595 894484 or

Contact Information

TWL Irrigation Ltd
Sales Office
Wilsonwells Croft, Crimond
Fraserburgh, AB43 8YH

Tel: +44 (0)1346 531193