摘要 |
A programmable control system with non-isolated inputs and outputs wherein an input device (PB1) is connected across a main supply (L1, L2) in series with an impedance (R1). A control input signal, derived from the input device (PB1), is fed via a second impedance (R2) to a digital logic system. (R2) is a considerably higher resistance than (R1), e.g. R2 = 10 x R1. |