We’ve been building thermocouple data loggers since 1993, when we introduced our first model—the SmartReader 6. It featured 8-bit resolution, which was very coarse for thermocouple ranges - but state-of-the-art for the time. Today’s SRX6 delivers 256 times more resolution/precision, and over 30 times the memory, reflecting decades of refinement in precision measurement, durability, and ease of use. Our long track record means you’re working with a product backed by years of real-world engineering and field experience.

Thermocouples are the world's most widely used type of temperature sensor, valued for their extreme temperature range, ruggedness, affordability, and flexibility. For a given thermocouple type, they're also reasonably interchangeable, making them a practical choice for use with devices that can accurately read their low voltage signals and convert them to temperature.

Read our full breakdown of why thermocouples are so widely used.

Yes, that is what the SRX6 was primarily designed for. It is compatible with standard thermocouples that follow the IEC or NIST voltage-temperature curves for Type J, K, T, E, or S. With the SRX6, there is no need for proprietary probes or connectors. You should be able to get reasonable accuracy as soon as you connect your 3rd party probe so long as you assign the correct thermocouple type to your input channel. For best results, use Special Limits of Error (SLE) thermocouples and consider calibration if your application demands NIST-traceable high accuracy.

Calibration is not required for the SRX6 to operate, and many users achieve good results using off-the-shelf thermocouples without calibration—especially when tracking trends or comparing relative temperature changes. In many applications, understanding how temperature moves over time or comparing readings between locations is more important than knowing the exact absolute value. For this, consistency and relative accuracy are often sufficient. 

However, if your application requires higher precision or traceable data—such as in validation, compliance, or quality-controlled environments—calibrating your logger and thermocouple together (either single-point or multi-point) can significantly improve accuracy. ACR offers calibration services tailored to your operating range and probe setup.

Yes. Our loggers have a high input impedance (>2 MΩ), which means they won’t load down the signal from a thermocouple simulator or a fine-gauge thermocouple wire. This ensures accurate readings during calibration and in the field, even with long cable runs. Some loggers with lower input impedance can distort simulator output, leading to inaccurate readings — an issue you won’t run into with the SRX6.

Besides ACR's thermocouple options, you can also source compatible probes through our authorized resellers or from a wide range of reputable third-party vendors. Thermocouples follow well-established standards, so you’re not limited to a single supplier—giving you flexibility to choose based on your application, budget, or preferred brand. If you need assistance, please contact ACR and we'd be glad to help.

Knowing your thermocouple type is essential before wiring it to your logger or configuring software. Our User Guide explains how to identify it reliably.

• One SRX6 Thermocouple Data Logger
• USB Interface cable
• License and link to download ACR TrendReader TRX Basic Software

No, thermocouple probes are not included by default. Most users already have their own probes or prefer to choose specific types and lengths suited to their application. However, we do offer a selection of compatible Type J, K, and T thermocouples through our online store. The SRX6 works with standard thermocouples that have bare wire ends—no special connectors required.

The SRX6 introduces several key improvements over the SmartReader Plus 6, including:

• Higher resolution: Upgraded from 12-bit to 16-bit, providing 16 times greater precision as well as improved accuracy.
• Increased battery capacity: Still rated for up to 10 years, but with a larger battery that offers more headroom—especially valuable in applications with frequent sampling, complex alarms, or heavy downloads
• Simplified connectivity: Uses a standard USB interface—no proprietary interface cable required
• Two-stage alarm support: Enables both warning and critical thresholds for more advanced monitoring.
• Flexible logging schedules and portable equations per channel—stored directly on the logger so data can be correctly interpreted on any computer, without relying on the original setup.
• Compatibility with TrendReader TRX software, which is also backward compatible with legacy SmartReader loggers.

For a full comparison, see the SRX6 Comparison Page in our User Guide.

We've designed the SRX6 to match or exceed all of the features in our SmartReader Plus 6 model—in fact, you're getting higher performance at a lower cost. That said, there are a few tradeoffs to be aware of:

• Sampling Speed: The SRX6 does not support ultra-fast sampling rates (faster than once every 10 seconds), which were possible on the SRP6 when used with an external battery pack. However, fast sampling is rarely practical or necessary for thermocouple applications and often results in unnecessary data and reduced battery life.
• Software Compatibility: The SRX6 is not compatible with older versions of TrendReader software (3.0 and earlier). Instead, it works with TrendReader TRX (Basic or Pro versions). The good news is that TRX software is backwards compatible, so you can use it to manage both legacy SmartReader loggers and your new SRX loggers from a single interface.

For most users, the upgrade brings improved convenience, broader compatibility, and significant savings without losing essential functionality. If you’re unsure how the upgrade will affect your workflow, feel free to reach out—we’re happy to walk you through the details.

The SRX6 is ready to use out of the box, but depending on your application, you may want to consider the following optional accessories:

• Thermocouple probes – Choose Type J, K, or T probes suited to your required temperature range and environment. The SRX6 accepts standard bare-wire thermocouples.
• Strain Relief Box – Helps protect external wiring by relieving mechanical stress on the terminal block, especially useful in field deployments or mobile setups.
• Weatherproof Logger Box – Adds environmental protection for outdoor or industrial use where moisture or dust is a concern.
• Crushproof Logger Box – Provides added physical protection in rugged environments like construction sites. Contact ACR using the form below for more information on this product.
• Spare 11-pin Terminal Blocks – Useful for quick replacements or when setting up multiple measurement points in rotation.
• Alarm Interface Module – Enables connection to external visual or audible alerts, helpful when immediate local notification is needed. Contact ACR for more information about this module.

For most SRX6 users, the Basic version should be adequate. For a complete list of differences between the Basic and Pro versions, please visit acrdatasolutions.com/trxpro

Yes, the SRX6 internally measures millivolt signals and even supports custom equations, so it is technically possible to use it for logging non-temperature millivolt sources. However, this is not its intended use. The input range and resolution are specifically optimized for thermocouple signals and the device includes cold junction compensation designed for temperature applications. If you're considering using the SRX6 for general-purpose millivolt measurements, ask yourself whether the accuracy, input range, and sampling behavior align with your application. In most cases, a general-purpose voltage logger would be a better fit.