Way back when i was a sysadmin, i recall reading a quote from one of the ATT greybeards who said something to the effect of “every competent sysadmin should be able to build his own network card”. Of course most of us have spent tons of time ripping apart electronics and “watching what happens when you connect X and Y”, but unlike the electronic engineers with their oh-so-cool multi-meters ive never actually done any plc programming..