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Interactive Controls Demo

Robot-to-PLC handshake simulator

A live model of the four-way handshake I use to coordinate a FANUC robot with a PLC during machine tending — request, acknowledge, complete, and clear — with auto/manual modes, non-critical status flags, and fault, hold, recover, and abort behavior. It runs entirely in your browser with original code; no customer logic is exposed.

Why A Four-Way Handshake

Neither side moves until the other confirms — so no edge is ever missed.

A two-way pulse can be lost if one controller scans slower than the other. A four-way handshake makes every transition wait for confirmation: the PLC requests, the robot acknowledges, the robot reports complete, then the PLC clears the request before the robot clears its flags. That interlock is what keeps a cell recoverable when something stalls mid-cycle.

HMI Status
IDLE
Mode
Auto
Command
Handshake phase
Idle
Cycles complete
0

Press Run to start the tending cycle.

Four-Way Handshake
PLC Cell controller
1 · REQUEST
2 · ACK
3 · COMPLETE
4 · CLEAR
ROBOT FANUC R-30iB
PLC → Robot (outputs)
    Robot → PLC (inputs)
      Non-critical status flags
        Signal timing chartnewest →

        Original demonstration logic. Signal names, the command sequence, and timing are illustrative of general integration practice and do not represent any specific customer's program.