+ Check if the terminal connection is working properly.
+/ Repeat the last command.
+BFC Boiler fault code.
+C=id Establish communication to the bus. The `id` parameter specifies the Application Layer Protocol ID (0OpenTherm Plus,1Ariston BridgeNet eBus,2Ariston Legacy eBus,3Ariston Legacy Serial,4Vaillant eBus,5Vaillant Serial,6Bosch EMS,7Immergas MODBUS), which is a numerical identifier for the specific protocol that the application software will use to communicate with the boiler. 
+C=? Display supported Application Layer Protocols. can be used to query the supported Application Layer Protocols that are available for use in the system.
+C? Display current connection state 1 - Not Connected, otherwise ALP id will be displayed
+CHM Enable or disable central heating mode.
+CHS Set central heating water temperature set-point in degrees Celsius.
+CHSB? Get maximum central heating water set-point upper and lower bounds for adjustment in degrees Celsius.
+CHWP? Display boiler central heating water pressure in bar.
+CHWT? Display boiler central heating water temperature in degrees Celsius.
+D Terminate communication to the bus. Just call +D without parameter.
+DHWF? Display water flow rate through the DHW circuit (liters per minute).
+DHWM=mode Domestic hot water mode enable or disable 0 - Disable, 1 - Enable
+DHWM? Read value of domestic hot water mode. 0 or 1
+DHWS Set domestic hot water temperature set-point in degrees Celsius. 
+DHWS? Read value of domestic hot water temperature set-point in degrees °C.
+DHWSB?