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Digital IO - CURRERA voltage logic


All Digital Inputs and Outputs are located on System Port.

Digital Outputs (GPO1-4)

Isolated sourcing outputs, high side switched.
Each Digital OUTPUT has an high side switch with common voltage source (Digital Output VCC (DO VCC)) for all four Digital OUTPUT signals.
A power source 7-42V must be provided to GPO VCC.

When a Digital OUTPUT signal is ON, Digital OUTPUT is closed to DO_GND.
When a Digital OUTPUT signal is OFF, Digital OUTPUT is floating.

Connecting devices to CURRERA

The exact connection between CURRERA R, the external device and its power source depends on the type of external device.

  • NPN-compatible device: All devices with an input that is enabled when it is grounded. A NPN-compatible PLC device does not provide power for the connected device (sinking input).
  • PNP-¬≠compatible device: all forms of external devices that are programmable logic controllers with PNP transistor types. A PNP-compatible device has an input that is enabled when it receives a voltage (sourcing input).
  • Transistor-transistor logic (TTL): These devices expect the connected device to provide the necessary voltage. For this purpose Digital Outputs +5V source, connected to pull-up resistors on Digital OUTPUT pins, can be used.
  • Inductive load: This category includes all devices that have an inductor wiring, such as small motors or relays. This type of devices requires requires external electronic and must not be connected directly to GPO

Connecting Digital OUTPUT to a NPN-compatible device

To connect CURRERA to a NPN­- compatible device, connect device ground to Digital Output GND.
The Digital OUTPUT signal must be connected to the device's sourcing input.
Pull down resistor need to be placed between device input and ground to provide proper operation.
The value of resistor may be sufficient for used load, however it must not be smaller than R = Vcc/1A. Otherwise high side switch may be damaged.
The logic will be inverted.

Connecting Digital OUTPUT to a PNP-compatible device

This type of device may be connected directly without any additional components.
Care must be taken only with consumption of device inputs.
It must not exceed 1A.

Connecting Digital OUTPUT to a TTL device

To connect CURRERA to a TTL device you need to connect the external resistor divider between a Digital OUTPUT signal and device inputs.
Resistor values may be R1 = (Vcc-5V)/5V * R2.
For example for Vcc = 12V it could be R1=4.7kOhm, R2 = 3.3kOhm.

Connecting Digital OUTPUT to an inductive load

Do not connect inductive load directly to CURRERA Digital OUTPUT.
Transistor have to be used to prevent damage of output.
See image below for proper connection.
Rp resistor can be connected to Digital Outputs +5V source to provide necessary bias current for transistor.
You should also use external diode to protect transistor from over voltage while disconnecting inductive load.

 Long wires can behave like inductive load. 

 !! Beware that only 1A can Digital Output source. 
Other wise Digital OUTPUTs may be damaged !! 

Digital Inputs (GPI1-4)

Comply with IEC 61131 - 2

Logic levels
LOGIC 0 I<0.5mA (U<5V)
LOGIC 1 I>5mA (U>11V)

Maximum ratings:

I in - 12mA
U in - 24V

Example of usage

Connecting LED

To calculate appropriate serial resistor you can use following equation:
R = (Vsource - Vd)/Id
Where Vsource is Voltage of used source.
Vd is forward voltage of used LED. (For red diode it may be about 1.3V)
Id is desired current trough LED.

See Handling of Digital Outputs in xiAPI

Connecting Button to Digital Input

To use button you need to connect button between voltage source 7-42V and Digital INPUT.
You need also connect Digital Input GND to ground of used voltage source.

See Handling of Digital Inputs in xiAPI

Connecting Button to Digital Input with debounce

Most buttons generate voltage spikes when depressed or released.
To overcome this problem, there is need to add debouncing circuit as on the following scheme.

Or setup internal debounce for CURRERA inputs.

See Debounce of Digital Inputs in xiAPI