The module monitors electrolysers for hydrogen production, fuel cells for electricity production and batteries. It records and transmits the voltages of individual cells or cell groups within electrolysis or fuel cell stacks and batteries. To do this, it measures the voltage difference between two consecutive channels, that are connected, for example, to the poles of a cell in a stack. Up to 15 individual voltages can be monitored per module. In total, an I/O station can monitor total voltages of up to 1200 V DC.