Digital and Analog Signals: Input and Output Channels

Digital Awareness

When you want to receive digital information from the outside: The business card input channels are available, usually in groups of 8 bits, to which binary information is assigned by a program. These can be assigned to an internal variable state of a byte by a reading instruction that may have a port. There can be one or more bytes of input, assigning each an address.

Analog Outputs

To send analog control signals to the outside, the tallies have one or more channels of output through their respective A/D converters. A 1V analog converter generates a constant proportional to the numerical value of the digital data that it has on its input lines. Internally, they have a 5V memory. Different voltage ranges can be obtained using external references; their values are usually limited from -10V to +10V. Not all have this possibility. The output channels can work in unipolar mode, with voltages always positive, or in bipolar mode with output ranges that span positive and negative voltages. Another feature is the resolution of the converter. A resolution of n bits indicates that it divides the range of voltages into 2ⁿ, resulting in a minimum voltage jump when changing the last bit equal to one such part. Medium-quality cards can use 12-bit converters. The basic programming of these outputs is achieved by sending the bits of the converter input through the bus. For 8-bit buses, the lowest bit must be sent first, and then the remaining 4. The 12 bits are retained in the input converter to match up with a new script. This double transfer will be the rate-limiting factor in the process. They are used to generate specific waveforms or excitation signals more complex than merely digital signals.

Analog Inputs

Enable the capture of analog signals from the outside. The card comes equipped with multichannel analog inputs, making possible the simultaneous handling of these signals. The signal connection to the business card can perform common or unbalanced inputs and differential mode.

Digital Output

These are in the business card to allow communication between the business card and control instruments. Another common use is to control two-state systems, connect and disconnect relays, power on and off lights, etc. They are programmed with 8-bit words so that each connector pin output can take the states 1 or 0. The sending of 1 byte is done through a program of writing instruction at the port, which is assigned a check. The word sent will remain on hold with a match until a new writing is sent.