The many similarities between the ladder diagrams used to program PLCs and the relay ladder logic When a PLC is used primarily to replace relays, timers, and counters, it's hard to beat the simplicity ...

A malfunction is nearly always on the input side or output side of the PLC. The ladder diagram shows you what the inputs and outputs are, and it shows how each output responds to a given input change.

This is a schematic of pPSU1 and pPSU2 plasmids. The 1000-base-pair (1 kb) ladder is made by cutting the two plasmids with the restriction enzyme, EcoRV. The 100-base-pair (bp) ladder is made by ...