ESP8266 WIFI relay network relay

1 – The power input terminals.
2 – The relay output terminals.
3 – IO input terminal.
4 – Enter the status indicator, IO input high when lit, blue light.
5 – The relay output status indicator, the relay is turned on, the red light.
6 – TTL serial output.
7 – Boot mode selection jumper.

Board Connectors

Here are the connections on my board:

A: 7-30V+ DC power supply
B: Power supply ground
C: Normally closed (NC) relay contact
D: Common (COM) relay contact
E: Normally open (NO) relay contact
F: 5V+ out
G: ESP8266 GPIO5 Optocoupler Input
H: Ground (isolated optocoupler input)