USB PC Interface with 15 digital inputs & 16 digital outputs

Here the scheme of card is shown with 15 inputs and 16 outputs to connect to a PC USB port:

plc programming software
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Scheme description


The card has the following parts:


Power: the circuit must be fed with a DC voltage from 6 to 9 volts, as it uses the voltage regulator 7805. This part of the circuit will fed all the components and also the output relays. 15 Digital Inputs: all the inputs are isolated by the CNY17 component, to activate it you will need to join the contact input connectors (1 with 2, 3 with 4, etc..)16 Digital outputs: UN2803 has been used (NPN Darlington transistors) to amplify the intensity of current needed to drive the relay coils. The relay voltage feeding it is the same as that of the general power because of the chosen relays works with 5 Volts.A Microchip PIC18F4550 that is responsible for management logic and digital signal communication with the PC. Will require a 20Mhz oscillator to provide clock signal and the capacitors to stabilize tensions.


The program that you must write in the micro controller can be downloaded from this link:


Program for PIC18F4550 USB Interface with 15 I/16O


To use this card with EasyPLC you have to select the external driver Nirtec_USB_1516_Card. This driver must to be configured with the card serial number, the firmware here available has the serial number IO_0001.


If you want to use more that one card connected to the same PC then you will need a firmware with a different serial number. Send an e-mail to to request information about how to obtain firmwares with other serial numbers.


The first time you connect the card to your PC, Windows recognizes a new hardware and prompt you for the drivers, you can download them here:


Windows XP / Vista / W7 drivers for Nirtec USB 1516 card


How to install the Nirtec USB 1516 card in Windows 7 x64 bits


Note: you will need the EasyPLC registered version to use the driver Nirtec_USB_1516_Card