Siemens analogue input module thermocouples thermometer current and voltage siemens 6es7231 4ha30 0xb0 the siemens 6es7231 4ha30 0xb0 sb 1231 is an analogue input signal board that converts analogue signals from current or voltage differential inputs and processes them into digital signals for internal processing by the simatic s7 1200 with analogue signal boards users can optimally adapt their controllers even to more complex tasks the signal board is plugged directly into the simatic s