Manglemender
Member
In the dim and distant I worked as a maintenance man in a plastics factory and my first interractions with PLC's was AB PLC2 systems programmed with the big old Grey Goose terminals. I only did backups and restore lost programs on those but we also has little Mitsubishi PLCs with a hand held programming terminal where you enterred instructions one at a time in STL.
All of the PLC gear was infinately preferable to the older machines built with sequence relays that made use of make before break contacts and timers all over the place. Fault finding on those was a complete nightmare as a machine might drop out of sequence only once or twice a shift so you ended up sitting in front of the panel following the sequence with your finger and trying to see which relay dropped out or didn't pull in. No wonder I haven't got any hair!
All of the PLC gear was infinately preferable to the older machines built with sequence relays that made use of make before break contacts and timers all over the place. Fault finding on those was a complete nightmare as a machine might drop out of sequence only once or twice a shift so you ended up sitting in front of the panel following the sequence with your finger and trying to see which relay dropped out or didn't pull in. No wonder I haven't got any hair!