Digital inputs and outputs
Digital, or binary, inputs and outputs are connected in groups with a common terminal. The M400 and M410 have common terminal in pairs, the ground terminal at other modules is common for all 8 inputs. The inputs must be powered by 24 V AC, potential-free inputs for dry contacts are only at room units and controllers UI… / UC… / FC…, see the data sheets.
All inputs are separated by optotransistors. It is possible to power them from the same source which is used as power supply for the modules. The maximum admissible voltage at the input is 50 V.
Beware the correct polarity when using DC voltage at the inputs: the input must be positive, COM or DGND must be negative.
Digital output modules are equipped with following components:
M200, M210, M215, MCIO2, MXIO, MMIO (3x): mechanical relays 230V / 5A, NO or changeover contacts – see data sheets of the modules.
MMIO (4x), UI…, : solid state relays (SSR), zero-switching, for DC or AC load. Maximum admissible current is 0.4 A, which is OK for a contactor or up to 2 thermic valves for radiators or fan-coil units.
The main advantage of a SSR is that it is noiseless and has no limitation regarding switching cycles. These outputs are thus suitable for pulse-width modulated signals (PWM), also known as quasi-analogue control. This is how the thermic valves or power semiconductor relays are controlled.
M300, M320: transistor with open collector. A semiconductor element is used to switch an external relay or contactor, or an indication element such as a LED or small bulb. Recommended circuitry must be used:
The diode, which is on the PCB of the output module, protects the transistor from voltge peaks which originate at the contactor relay at the moment of disconnection. The power voltage is 24 V DC, this voltage must be available in the panel, preferably from an industry switched power supply.
Digital inputs and outputs states are indicated by LEDs at the front panels of the modules.