Update README.md

add RS232 via USB style guide

README.md

@@ -16,14 +16,20 @@ Search for "SAJ Inverter Modus" and install it.
 
 After reboot of Home-Assistant, this integration can be configured through the integration setup UI
 
-## Connection via Modbus TCP to a SAJ Inverter
+## Connection via Modbus TCP to a SAJ Inverter via the RS485 port
 Connect a Modbus to Wifi device to the Modbus port of your SAJ Inverter.
-I use a Hi-Flying Elfin-EW11 (www.hi-flying.com/elfin-ew10-elfin-ew11).
+
+Guide below uses a Hi-Flying Elfin-EW11 (www.hi-flying.com/elfin-ew10-elfin-ew11).
 
 **Cable Layout for EW11A to SAJ Inverter:**
 
 Both connectors are RJ45.
-![cable](https://github.com/wimb0/home-assistant-saj-modbus/blob/main/images/cable.png)
+| SAJ RJ45 pin | Function | EW11 RJ45 pin |
+|----------|----------|----------|
+| 2        | GND_W    | 8        |
+| 3        | +7V_W    | 7        |
+| 7        | RS485_A+ | 5        |
+| 8        | RS485_B+ | 6        |
 
 **EW11A settings:**
 
@@ -40,5 +46,38 @@ Both connectors are RJ45.
 * Cli Disable
 * Protocol Modbus
 
+
+## Connection via Serial TCP to a SAJ Inverter via the USB port
+Connect a Modbus to Wifi device to the USB style port of your SAJ Inverter.
+
+Tested using a Hi-Flying Elfin-EW10 (www.hi-flying.com/elfin-ew10-elfin-ew11).
+
+**Cable Layout for EW10 to SAJ Inverter:**
+
+Cut an old USB-A cable and connect as follows:
+
+| USB pin | Function   | EW10 pin |
+|---------|------------|----------|
+| 1       | +7V        | 7        |
+| 2       | RS-232 RXD | 6        |
+| 3       | RS-232 TXD | 5        |
+| 4       | GND        | 8        |
+**EW10 settings:**
+
+**Communication settings:**
+* Configure Tcp Server, choose a port number.
+* Security: Disable
+* Route as Uart
+
+**Serial port settings:**
+* Baudrate 115200
+* Databit 0
+* Stopbit 1
+* Parity None
+* Flow Control Settings Disable
+* Cli Disable
+* Protocol Modbus
+
+
 [![saj_logo](https://github.com/wimb0/home-assistant-saj-modbus/blob/main/images/saj_modbus/logo.png)](https://www.saj-electric.com/)