I purchased on EBay a wireless 4 button remote control with 4 channel receiver for less than $5.00.
An example is here: https://www.ebay.com/itm/IC-2262-2272-4-CH-Key-Wireless-Remote-Control-315MHZ-Receiver-module-F-Arduino/182052405208?has…
I put a 5 volt voltage regulator on the 24VDC output of the PLC and wired the 4 outputs to an Allen Bradly TTL Sourcing input card. Since the receivers outputs are sourcing when high, the PLC see's all 4 inputs always on, so I check if only one of them goes off - then I know a button is pressed. I found that the receiver will respond to 2, 3, or all 4 buttons pressed at the same time, so I wrote in some logic to ignore if more than one is on, and reset any mode if 2 or more are held on for a few seconds.
My first version of the program I controlled 4 outlets on a power strip I rewired to individually controlled outlets (every power strip I buy I look on the back to make sure it is assembled with screws and not welded together so I can modify the hot side)
After controlling 4 things for a while I worked out a way to have the 4 buttons set 1 of 4 modes, then after the button is released the 4 buttons perform 4 separate functions In that mode - for a total now of 16 items controlled. Having 4 modes now is why I reset if I hold 2 or more buttons on together - to select a different mode. Also, any mode selected will time out after 12 seconds of no button press automatically.
Right now the setup is in my home office on a SLC5/05 controlling a floor lamp, a desk lamp, a LED computer fan, and a laser star projector to light up the ceiling (had an unused controlled outlet and it was nearby). The floor lamp is in "Security Mode" in which it turns on every night, but when it turns on it changes a pointer that changes the minute of he hour it turns off, and when it turns off it changes the start minute the next day - that way the on and off times are varied throughout the hour and don't appear like they are timer controlled. The remote control is set up to toggle the security mode, turn the light on for 1 hour when it is off if wanted, and turn the light off during the security time if not wanted. Of the 16 controls possible I only have 9 of them used as of now.
Message was edited by: Gregory Innes Fixed a couple of typo's