Elements of the modernization example system to be left hardwired

Large Relay System Modernization

This is an example of modernization for a machine control system. It will go from hardwired relay logic, to PLC programmed logic. With the exception of the ones that the controller can execute (e.g. timers and control relays), the field devices will not change. Modernizing this machine’s control system will bring many benefits: * A […]

PLC implementation of the circuit in Figure 23

Simple Relay Replacement use the PLC

This relay replacement example uses the PLC implementation for the electromechanical circuit in Figure 23. Figure 23: Electromechanical relay circuit. Hardware timer TMR1 requires instantaneous contacts in the first rung, which are used for latching the rung. If instantaneous TMR1 contacts were implemented using a PLC timedelay contact, then PB1 should be pushed until the

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