ODOT Temperature Acquisition Module Upgraded to Meet Expanded Industrial Site Needs

PT100 is a commonly used resistance temperature detector in the industrial control field, known for its high accuracy, good stability, linear characteristics, and wide temperature range. It is widely applied in industrial automation, temperature control systems, laboratory instruments, medical equipment, automotive industry, and other fields.

ODOT Automation’s independently developed C series remote IO modules, CT-3713 and CT-3734, perfectly meet the data acquisition requirements of PT100 sensors.

1. Product Introduction

CT-3713 has a measurement range of -240 to 880°C, with a measurement accuracy of 0.5°C. The module operates in an environment ranging from -35 to 70°C, with a resolution of 15 bits. The channels feature diagnostic functionality and support both 2-wire and 3-wire configurations.

CT-3734 builds upon the basic functions of CT-3713 by adding one additional channel, supporting a total of 4 channels for PT100 sensors, making the module more cost-effective. Additionally, the internal circuits between the 4 channels of CT-3734 have been optimized, providing isolation between channels and superior anti-interference capabilities compared to CT-3713.

2. On-site pain points

Using a particular customer as an example: when the customer is measuring the temperature of multiple detection points using CT-3713, if the M+ model line of one channel is disconnected, the temperature values collected from adjacent channels may fluctuate or remain unchanged.

ODOT engineers conducted on-site troubleshooting and found that the issue occurred when 10 units of 7.5 kW motors were simultaneously started, resulting in a radiation noise of 80Vpp measured at the PT100 probe.

Simultaneous startup of 10 units of 7.5 kW motors generates strong electromagnetic interference, creating radiation interference to surrounding equipment. At this moment, the PT100 cable acts as a receiving antenna. Without proper grounding at the end of the shielding layer, the interference signal couples onto the RTD cable and is then in series with the CT-3713 signal acquisition channel. This interference couples with adjacent channel circuits and forms a coupled loop with the system’s 0V and PE.

3. ODOT Automation Solution

Based on the on-site situation, ODOT engineers have provided the following solutions:

All terminal shielding layers of the PT100 sensor can be pulled together and connected to the PE terminal of the C series remote IO communication coupler to break its coupling loop, ensuring the normal operation of the module.

Replace CT-3713 with CT-3734. The four channels of this module have isolation capabilities. Connecting to any channel will break its coupling loop, ensuring the normal operation of the module.

ODOT Automation, as a member of the automation industry, has been committed to providing high-quality products and services to industry partners. In the future, ODOT will continue to focus on the industrial field, working together with industry partners to build open automation and serve high-quality intelligent manufacturing.