1. ◇：R ─ Relay output；T ─ Transistor SINK(NPN) output
J ─ Transistor SOURCE (PNP) output
2. Δ：2 ─ built-in RS232 port；U ─ built-in USB port (non-standard)
3. ◎：AC ─ 100~240VAC power supply
D12 ─ 12VDC power supply
D24 ─ 24VDC power supply
4.–C：Blank ─ Standard；–C ─ add in RTC
5. The unmarked frequencies of Digital Input (DI) or Digital Output (DO) are low speed.