VFD Signal Interface

The power input has been designed to receive 24VCC from VFD internal power supply. The NE555 has been wired at monostable operation, so when SW1 is pressed, U3 relay goes ON after timing configurated by C3 and R4. A TON and TOFF output is available, and the COM terminal must be wired with COM terminal of I/Os block from inverter. SW4 resets any action from the board, turning the relay U3 OFF immediatly.