Summary of INDUSTRIAL DIGITAL INPUTS WITH THE MAX22191
The MAX22191 parasitically powered digital input (DI) circuit converts industrial binary signals (e.g., pushbuttons, temperature or proximity threshold indicators) into reliable logic for PLCs and controllers. It supports monitoring Type 1 and Type 3 sink and source inputs and provides example circuits for current sink, current source, high-voltage, and AC detection applications per IEC 61131-2 DI type definitions.
Parts used in theMAX22191 Digital Input Project:
- MAX22191 parasitically powered digital input IC
- Industrial binary sensors (pushbutton, temperature threshold indicator, proximity sensor)
- Current sink circuits
- Current source circuits
- High-voltage detection components
- AC detection components
- Programmable logic controller (PLC) or industrial controller
- Passive components for interface (resistors, capacitors)
- Power supply or parasitic power arrangement
A digital input (DI) is a circuit designed to receive a binary signal transmitted from an industrial sensor and translate that input into a reliable logic signal for a programmable logic controller (PLC) or industrial controller.
Common examples of industrial binary signals are pushbuttons and/or temperature or proximity threshold indicators. The MAX22191 parasitically powered DI circuit can monitor Type 1 and Type 3 sink and source binary input signals for PLC and industrial circuits. This application note shows examples of current sink, current source, high voltage, and AC detection digital input circuits using the MAX22191.
Introduction
A DI is a circuit designed to receive a binary signal transmitted from an industrial sensor and translate that input into a reliable logic signal for a PLC or industrial controller. Common examples of industrial binary signals are pushbuttons and/or temperature or proximity threshold indicators. The MAX22191 parasitically powered DI circuit can monitor Type 1 and Type 3 sink and source binary input signals for PLC and industrial circuits.
Types of Digital Inputs
The IEC 61131-2 standard governs the input threshold and current requirements for sinking DI circuits in industrial applications and defines three types of DI circuits for industrial applications:
- Type 1: Electromechanical circuits
- Type 2: Discrete, high current, semiconductor circuits
- Type 3: Integrated (low power) semiconductor circuits
The differences between the DI types are primarily voltage thresholds and current limits. Additionally, DI circuits are typically used in one of two configurations:
Read more: INDUSTRIAL DIGITAL INPUTS WITH THE MAX22191
- What is the purpose of a digital input (DI)?
A DI receives a binary signal from an industrial sensor and translates it into a reliable logic signal for a PLC or industrial controller. - Which device is highlighted for parasitically powered DI circuits?
The MAX22191 parasitically powered digital input IC is highlighted. - What types of industrial binary signals are common examples?
Common examples include pushbuttons and temperature or proximity threshold indicators. - Which DI types does the MAX22191 monitor?
The MAX22191 can monitor Type 1 and Type 3 sink and source binary input signals. - What standard defines DI thresholds and current requirements?
The IEC 61131-2 standard governs the input threshold and current requirements for sinking DI circuits. - What are the three DI types defined by IEC 61131-2?
Type 1 is electromechanical circuits, Type 2 is discrete high-current semiconductor circuits, and Type 3 is integrated low-power semiconductor circuits. - In what configurations are DI circuits typically used?
The article notes DI circuits are typically used in sink or source configurations. - What example circuits does the application note show for the MAX22191?
It shows examples of current sink, current source, high-voltage, and AC detection digital input circuits.
