PC4's and PB4's are the power bars. Each has 4 outlets. The PC4 is the original. The PB4 replaced the PC4 a few years back. The PC4 has a current readback, but it is total current. The PB4 does not have the current readback, but it has a lager power supply for the buss and also has built in circuitry that allows use of low power pumps on CH2 and CH3 of the power bar. The SLX has a pH input, a pH or ORP input, temp input and two switch inputs. The SLX replaced the SL1 module. The SL2 module has a pH input, salinity input, temp input and two switch inputs. The SW5 module has four switch inputs and a relay output. The SL1 has a pH input, ORP input, temp input and two switch inputs. The HUB module is just a 5 way splitter for the buss. The NET module is a web interface to the system. It also will graph selected ports up to 16 I believe. It also has a email function for alarms, but it is hard to find a email service that supports it since it does not use the newer security protocols. It does allow some programming of ports. You cannot program timers or alarms via the NET. Also the NET module is not compatible with the Archon. It is not needed with it since the Archon is already web based. I left out several modules if you run across one the ones I left out let me know. I just covered the most common ones.
