General
Number of channels	4
Input type	Resistance sensors/thermocouples/resistance bridges (strain gauges)
Resolution	16 Bit
Diagnostic function
Intrinsic safety

The WAGO 750-489 is a 4-channel analog input, specifically designed for processing signals from resistance sensors, thermocouples, and resistance bridges (strain gauges). The device is used in industrial automation technology for precise acquisition and transmission of analog measurement values, for example from temperature or strain sensors. It is designed for use in safety-critical applications, as it features intrinsic safety, enabling its use in explosive environments. The integrated diagnostic function supports operational safety by detecting and reporting faults in the signal path or connected sensors.

Applications

The analog input 750-489 is used in process and factory automation, particularly in environments where temperature measurements via RTD sensors or thermocouples, as well as strain measurements via strain gauges, are required. Typical application scenarios include monitoring machine and plant components, temperature control in production processes, or recording mechanical loads. The intrinsic safety makes the device suitable for use in the chemical industry or mining, where explosion hazards exist.

Functions and Equipment in Detail

The device features four independent inputs, each designed for connecting a sensor. Signals are digitized with a resolution of 16 bits, ensuring high measurement accuracy and fine resolution of the acquired values. The integrated diagnostic function enables continuous monitoring of the input channels and can generate an alert in case of faults such as open or shorted lines or missing sensors. Intrinsic safety allows operation in Zone 1 and Zone 2 according to applicable standards for explosion-protected installations.

Technology Explained Simply

The 16-bit resolution means that each channel can distinguish up to 65,536 different values, ensuring precise measurement of small signal changes. Processing of resistance sensors (e.g. PT100, PT1000) and thermocouples (e.g. Type K, J, T) is handled by special input electronics that recognize the different signal types and linearize them accordingly. Resistance bridges (strain gauges) are also queried via a suitable input circuit, converting the bridge voltage into a digital signal. The diagnostic function checks the integrity of the signals and can detect disturbances in the measurement system at an early stage.

Compatibility and Accessories

The analog input is designed for use in the WAGO module system and can be mounted on standard support rails. Compatible support rails include, for example, the steel support rail 210-113 or 210-112, available in various versions (perforated, non-perforated, galvanized). For labeling modules, quick labeling systems such as the Mini-WSB (e.g. 248-501/000-002 yellow, 248-501/000-005 red) can be used. Additionally, shield clamps such as 790-108 or 790-216 are available to ensure electrical shielding of cables. For power supply, external power supplies such as 750-625/000-001 or 750-606 can be used, providing 24 V DC.

Mounting and Installation

Mounting is done on a DIN support rail, with modules secured by simple snap-in. The connection terminals are designed for connecting sensor cables, and the use of shielded cables is recommended, especially for long lines or in electromagnetically disturbed environments. Shield clamps ensure a secure connection of the shield to the support rail to minimize interference. Installation takes place in an enclosure or control panel, with environmental conditions meeting the requirements of the relevant standards.

Advantages in Operation

The combination of high resolution, integrated diagnostics, and intrinsic safety provides a reliable and low-maintenance measurement solution. The modular design allows flexible system expansion, and standardization of interfaces simplifies integration into existing automation structures. The diagnostic function reduces troubleshooting during operation, as potential problems can be detected and localized during operation. Use in explosive environments expands the range of applications and reduces the need for additional protective measures.