https://control.com/technical-articles/examples-of-digital-signals-in-control-systems/
Digital input modules are commonly used in data acquisition systems to capture and digitize signals from switches, sensors, or transducers. These modules enable the measurement and monitoring of discrete events or binary states in industrial, scientific, or research applications. Many microcontroller platforms feature digital input pins or modules that allow the microcontroller to sense and respond to digital signals.
https://control.com/technical-articles/analog-versus-digital-communication/
Digital communication is more abstract. The term "digital" can refer to either single discrete signals, or it can refer to the stream of binary data used by Ethernet, DeviceNet, Modbus, or nearly every other serial data stream.
https://control.com/technical-articles/analog-and-digital-signal-filtering-in-plc-systems/
The first step is to resolve the issue that is causing the false signal in the first place. With analog voltage inputs, use short wire runs, keep high-frequency signal wires out of the same duct as analog wires, add a signal filter between the amplifier and the input module, or use a digital signal converter.
https://control.com/technical-articles/examples-of-analog-signals-in-control-systems/
Industries involved in manufacturing, assembly lines, robotics, and machine automation often require precise control over physical variables. Analog signals are used for feedback control, proportional control, and regulating various processes. One common approach is to use digital communication protocols to transmit analog information already converted into binary digital numbers.
https://control.com/forums/threads/digital-and-analog-i-o-basic-info.2685/
Very simply... digital signals are either ON (binary 1) or OFF (binary 0). Digital input signals are used to represent items that only have two (2) states, such as... ON or OFF states ALARM or NORMAL conditions Similarily, Digital output signals ...
https://control.com/forums/threads/discrete-and-analog-signal-in-same-cable.19029/
In 1996 we installed a reasonably large DCS (3000 I/O) and did exactly what you propose. We used an Australian/New Zealand cable that had 24 unshielded twisted pairs with an overall screen. All the signals to and from the field boxes were either 4-20 mA for the analogs or 0-24 volt for the digitals.
https://control.com/textbook/digital-data-acquisition-and-networks/
One of the greatest advantages of digital technology over analog is the ability to communicate vast amounts of data over a limited number of data channels. In the world of 4-20 mA signaling (or 3-15 PSI signaling, for that matter!) each pair of electrical wires (or pneumatic tube) could communicate ...
https://control.com/technical-articles/how-to-use-analog-to-digital-converters-in-a-control-system/
The purpose of an analog to digital converter or ADC is right in its name, it takes an analog signal like temperature, pressure, or any signal voltage or current, and converts it to a digital equivalent representation. The analog signal may be between 0 and 5 volts, and the converted digital signal is in the form of an integer, and can range from 0 to 1024 or 0 to 65536.
https://control.com/news/dunkermotoren-puts-motion-control-inside-its-new-dgo-motors
These functions will be programmed into the motor at the factory, so when it is delivered to the OEM, it can be installed without commissioning or integration into a drive system. Simply provide digital signals for start, stop, and direction to control the motor.
https://control.com/forums/threads/4-20ma-in-long-distances.9456/
You can use multiplexers from MOORE (Cable Concentrator System, CCS modules), for 16 analog/digital signals (channels are configurable). Maximum distance with 24AWG twisted pair wiring is 2 miles (3.2Km).
https://control.com/forums/threads/digital-signals.43218/
Analogue signals from devices like PT or LT operate on 4-20 mA current. It starts from 4 mA and not 0 mA for lots of reasons, the main one being is that if there is a fault in the line, it will send a 0mA, the PLC might think that 0 pressure is there (or any physical quantity), but instead there is a fault in the line. What about Digital Signals: they are either High (24VDC) or Low (0VDC) doesn't the 0 V creates some sets of problems same with the Analogue signals?
https://control.com/technical-articles/tutorial-analog-signals-with-phoenix-contacts-plcnext-platform/
The format for the actual real-world process data items begins with the name assigned to the module, in our case “dio-1” for the digital I/O module, and “aio-1” for the analog module. Following the module name, add “/ IN” or “/ OUT” followed by the input number.
https://control.com/thread/1302859380
In plastic conduit, I would shield for sure. Metal conduit may actually render shielding ineffective due to transmission line effects. But you have to be more specific about "digital signals", a line from a microswitch is much, much, different from a RS485 cable.
https://control.com/forums/threads/interfacing-vfd-with-plc.26947/
Digital signals will include for example Start, Stop, Rotation CW, Rotation CCW, Jog, Set Speed 1, Set Speed 2 (these Set Speeds are from the drives parameter set), drive status, alarms...
https://control.com/news/belden-expands-it-ot-portfolio-with-new-connectivity-products/
The new Belden LioN-X IO-Link Analog Hubs let you bring existing analog sensors onto an IO-Link network without replacing the sensors. Each hub has four configurable analog ports for voltage, current, resistance, or thermocouple inputs, plus eight digital inputs.
https://control.com/textbook/digital-data-acquisition-and-networks/digital-data-communication-theory/
This very textbook you are reading was transmitted in digital form over the electronic network we call the Internet: a feat nearly impossible with any sort of analog electronic technology. The main benefit of digital data communication in industrial control is simple: no longer must we dedicate a single pair of wires to each and every variable we wish to measure and control in a facility as is necessary with analog (4-20 mA) signaling.
https://control.com/technical-articles/why-is-4-20-ma-current-used-for-industrial-analog-controls/
To convert 4-20 mA current to a 1-5 V digital signal, a simple 250 Ω precision resistor would do the job.
https://control.com/forums/threads/transmission-of-digital-and-anolog-signals-for-long-distance.36530/
You don't say what your DCS is, but most suppliers today have remote I/O capability. If yours has that capability, I recommend installing a small remote I/O cabinet at your local pump panel and then use a redundant fiber optic link to transmit the signals between the remote location and the control room.
https://control.com/technical-articles/analog-vs-fieldbus-systems-comparisons-and-advantages/
HART protocol is a hybrid protocol in the sense that it uses analog and digital communication over the same analog wires used for conventional 4-20 mA signals. Therefore, an additional digital signal can be superimposed using Frequency Shift Keying (FSK) on the 4-20 mA signal for additional information acquisition.
https://control.com/textbook/digital-data-acquisition-and-networks/digital-representation-of-numerical-data/
In order for any digital device to successfully interface with an analog signal, that signal must be digitized by means of an analog-to-digital converter or ADC. In general, ADC circuits receive analog voltage signals from sensors and output binary numbers (count values) proportional to those ...
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