Configuring or troubleshooting a field instrument can become unnecessarily slow when a technician must first locate a compatible power supply, loop resistor, communicator, ammeter, leads and supporting documentation.

The Emerson AMS Trex Device Communicator is designed to bring several of those functions into one rugged handheld platform. Depending on the generation, installed communication module and applications, it can help technicians connect to HART and FOUNDATION Fieldbus devices, power unpowered instruments, measure or simulate 4–20 mA loop signals, review device diagnostics and manage field-device configurations. Current-generation Trex documentation also includes support for Bluetooth-enabled devices.

For Canadian process plants, utilities, water and wastewater operations, pulp and paper mills, oil and gas facilities, mines, chemical plants, food-processing facilities and instrumentation contractors, renting an AMS Trex can make sense when the communicator is needed for:

• A commissioning project
• A plant shutdown or turnaround
• Temporary troubleshooting
• Bench configuration
• An emergency replacement
• A short-term maintenance campaign
• Additional capacity for several technicians
• Evaluating the platform before purchasing

The exact capabilities depend on the rental unit. Before booking, confirm whether the kit contains a legacy AMS Trex or the newer AMS Trex 2, which communication module is installed, which device applications are licensed, and whether the unit has the approvals required for the intended work area.

What Is the Emerson AMS Trex Device Communicator?

The AMS Trex is a handheld field-device communicator for commissioning, configuring, diagnosing and troubleshooting intelligent process instruments.

Current Emerson information says the platform supports a library of more than 2,500 HART and FOUNDATION Fieldbus devices from Emerson and third-party manufacturers. The latest generation also adds communication with supported Bluetooth-enabled devices.

Depending on the configuration, technicians can use it to work with devices such as:

• Pressure transmitters
• Temperature transmitters
• Flow instruments
• Level transmitters
• Valve positioners
• Digital valve controllers
• HART instruments
• FOUNDATION Fieldbus devices
• Supported Bluetooth-enabled field instruments

Electronic Device Description Language technology allows the Trex to communicate with supported devices from different manufacturers using the appropriate device descriptions. Device support should still be checked before rental because a communicator may need the correct, current device description for the exact manufacturer, model and revision.

Why Rent an AMS Trex?

Use It for a Specific Project

Purchasing a communicator may not be economical when it is only needed for one commissioning project, outage or troubleshooting campaign.

Rental allows a team to use the equipment for the required period without adding a permanently owned asset that will also require ongoing software management, battery maintenance, support and calibration.

Add Capacity During Shutdowns

Turnarounds and shutdowns often require several technicians to work on devices at the same time.

Renting additional communicators can help teams complete configuration checks, loop work and device validation in parallel rather than sharing one instrument across several work areas.

Replace an Instrument Temporarily

A rental unit can help maintain work continuity while an owned communicator is:

• Being repaired
• Receiving updates
• Undergoing calibration
• Waiting for a replacement battery
• Temporarily assigned to another site

Evaluate Before Purchasing

The Trex platform is available with different hardware modules, applications and service options.

A rental period can help an organization determine:

• Which communication module is required
• Whether Power the Loop is valuable for its workflow
• Which applications technicians actually use
• Whether the unit works with its installed device population
• Whether a current-generation Trex 2 upgrade is justified

Power the Loop: The Main Workshop Advantage

The original JM Test article focuses on the time lost when technicians bring a field device into the workshop but must first assemble a power supply, loop resistance and communicator before checking it.

Power the Loop is designed to simplify that workflow.

With a suitably configured Trex and the Device Communication Plus module, the technician can connect an unpowered compatible instrument to the powered terminals and use the handheld to supply device power. Emerson says this allows devices to be configured before permanent power and I/O infrastructure are installed.

Potential benefits include:

• Less time locating an external power supply
• Fewer separate tools on the workbench
• Faster pre-installation device checks
• Easier commissioning before the control system is available
• Simplified troubleshooting of removed instruments
• Reduced setup time during outages

Power the Loop is not available in every possible Trex configuration. Confirm that the rental includes the Device Communication Plus module and the leads required for the intended device.

Bench Configuration and Pre-Installation Checks

Before a transmitter or positioner is installed, the Trex can support several checks when the correct module and connection method are used.

Emerson’s current user guidance describes using the Trex to:

• Power a transmitter
• Measure its 4–20 mA output
• Power a positioner
• Control current to check positioner movement
• Simulate a transmitter output
• Verify that a control system reads the expected current
• Check loop voltage
• Diagnose portions of a HART loop

This can be useful for identifying problems before the instrument reaches the field.

For example, a technician may confirm that:

• The device powers up correctly
• The tag and configuration are correct
• The range and engineering units match the project
• The output responds as expected
• The control-system input reads the simulated signal
• A valve positioner moves through the intended range
• The correct device description is available

Catching these issues on the bench is usually easier than discovering them after installation.

HART Device Communication

HART devices combine a 4–20 mA analogue process signal with digital communication.

An AMS Trex can connect to supported HART instruments to help technicians review:

• Device identity
• Tag information
• Process variables
• Status and alerts
• Configuration parameters
• Ranges and units
• Diagnostic information
• Maintenance information

The Trex may also support configuration changes and device-specific service procedures where those functions are available through the installed device description.

The current platform’s device library supports a large range of Emerson and third-party HART and FOUNDATION Fieldbus instruments, but exact compatibility should be checked before rental.

FOUNDATION Fieldbus Work

The Trex can also connect to supported FOUNDATION Fieldbus devices and segments.

Depending on the installed module and applications, it can assist with:

• Device configuration
• Segment troubleshooting
• DC voltage review
• Average-noise checks
• Communication diagnostics
• Device status and alerts

Emerson describes the Trex as capable of diagnosing network DC voltage and average noise on FOUNDATION Fieldbus segments and checking whether HART loop voltage is appropriate.

Technicians should confirm that the rental includes FOUNDATION Fieldbus capability. A HART-only configuration will not necessarily meet a Fieldbus project requirement.

4–20 mA Loop Diagnostics

With the appropriate Device Communication Plus module, the Trex can support several 4–20 mA loop tasks.

These can include:

• Measuring loop current
• Measuring loop voltage
• Sourcing or controlling current
• Simulating a transmitter
• Powering an instrument
• Checking the control-system input
• Checking the control-system output
• Isolating portions of a loop during troubleshooting

The current Trex 2 user guide describes current measurements from 0 to 25 mA on a 4–20 mA loop and includes detailed warnings about correct ammeter connection. It specifically warns not to connect ammeter terminals in parallel with a powered current loop because the low resistance can disrupt the loop and cause incorrect device behaviour or unexpected positioner movement.

These functions should only be used by technicians who understand process-loop wiring, control-system behaviour and the operating state of the equipment.

Legacy AMS Trex vs Current AMS Trex 2

This distinction is important for the Canadian rental page.

Legacy AMS Trex

The original JM Test article and its accessory description refer to the earlier AMS Trex generation.

That platform supports HART and FOUNDATION Fieldbus communication, Power the Loop with the Plus module, valve diagnostics, loop troubleshooting, Wi-Fi or USB data transfer and a pre-installed device-description library. Its 2023 product data sheet lists a 14.5 cm touchscreen, approximately 1.33 kg weight and more than eight hours of typical battery operation.

AMS Trex 2

Emerson announced the redesigned version in October 2025.

The current generation adds or improves:

• Faster hardware
• A modern operating system
• Greater memory
• Updated security
• Bluetooth HART connectivity
• Support for calibration-oriented workflows
• Improved current measurement and sourcing accuracy

The AMS Trex 2 documentation refers to two module levels:

• Device Communication Module: HART and FOUNDATION Fieldbus communication
• Device Communication Plus Module: communication plus ammeter, Power the Loop and Loop Diagnostics functions

A rental listing should identify which generation and module are supplied rather than using “AMS Trex” as if every unit has identical capabilities.

Calibration Capability: Confirm the Exact Generation

This is one of the most important updates missing from the original article.

Emerson states that measurement tolerances on the legacy Trex were intended for reference use rather than official calibration work. The redesigned Trex 2 with the appropriate Plus module supports traceable current measurement and sourcing for calibration-oriented activities.

Emerson’s current Trex 2 material lists:

• Current-control range from 3 to 22.5 mA
• Current-measurement range from 0 to 24 mA
• Resolution of 1 µA
• Published accuracy specifications for the supported module
• Optional full NIST calibration with test data

For Canadian users, do not assume that every rental Trex can serve as an official calibrator.

Before renting for calibration work, confirm:

1. The unit is the current Trex 2 generation.
2. It includes the Device Communication Plus module.
3. Its calibration is current.
4. The certificate contains the documentation required by your quality system.
5. NIST traceability is acceptable under the customer’s Canadian QA requirements.
6. The measurement range and uncertainty are suitable for the task.

A calibration certificate and a device-communication rental are not automatically the same thing.

Valve Diagnostics

The AMS Trex can also support valve work through compatible applications such as ValveLink Mobile.

Depending on the Trex configuration and digital valve controller, technicians may be able to:

• Review valve condition
• Check configuration
• Troubleshoot device alerts
• Run valve signatures
• Review step response
• Perform dynamic error-band testing
• Power compatible valve controllers with the Plus module

Emerson describes ValveLink Mobile as supporting HART and FOUNDATION Fieldbus Fisher FIELDVUE digital valve controllers and allowing certain diagnostics without removing the valve from service.

Application licensing and supported device models should be confirmed before rental. Do not assume every Trex kit automatically includes every Emerson application.

Device Configuration and Data Management

The Trex is designed to make device information available as soon as a supported device is connected.

Depending on the installed applications, technicians may be able to see:

• Device manufacturer
• Device type
• Tag
• Status
• Alerts
• Primary variables
• Configuration menus
• Device diagnostics

Current Emerson platforms can also synchronize field changes with AMS Device Manager through Auto Sync, helping maintain an audit trail of configuration changes.

This feature matters most when the renter’s organization already uses AMS Device Manager and has the necessary connectivity, licenses and data-management process.

For a stand-alone rental, confirm how configurations and results will be:

• Saved
• Exported
• Transferred
• Returned to the customer
• Removed from the rental instrument afterward

What Should Be Included in an AMS Trex Rental Kit?

The original US article states that its rental kit includes the communicator, case, leads, clips, power supply, charger, stylus, straps, manual, current software and paperwork.

Do not automatically copy that promise to the Canadian page unless JM Test Canada confirms the current package.

A Canadian rental quote should identify:

• Trex generation
• Main communicator
• Communication module type
• HART capability
• FOUNDATION Fieldbus capability
• Power the Loop capability
• Loop Diagnostics application
• ValveLink or other licensed applications
• Test leads
• Clips and connectors
• Charger and power adapter
• Battery condition
• Protective case
• Hand or shoulder straps
• Magnetic hanger, where included
• Device-description update status
• Firmware and operating-system version
• Calibration certificate, where required
• Hazardous-area approval and marking
• User guide or quick-start documentation

The exact accessories matter. A Trex without the required communication module or lead set may not perform the intended task.

Rental Compatibility Checklist

Before ordering, provide the rental team with the following information.

Communication Protocol

Confirm whether the project involves:

• HART
• FOUNDATION Fieldbus
• Supported Bluetooth devices
• More than one protocol

Device Information

Provide:

• Manufacturer
• Model
• Device revision
• Protocol revision
• Required device description
• Application or diagnostic requirement

Required Work

Clarify whether you need to:

• Configure devices
• Power an unpowered device
• Measure loop current
• Simulate a transmitter
• Source current
• Troubleshoot a loop
• Diagnose a valve controller
• Work on FOUNDATION Fieldbus segments
• Perform a documented calibration

Work-Area Classification

Confirm whether the instrument will be used in:

• A general-purpose area
• A classified hazardous area
• A location requiring a particular intrinsic-safety approval

Intrinsically safe versions are available, but the marking on the exact unit must match the area classification and applicable site requirements. The earlier Trex product documentation lists CSA approvals for US and Canadian hazardous-area use among its available global intrinsic-safety certifications.

Rental Period and Location

Provide:

• Required delivery date
• Project start date
• Expected return date
• Canadian worksite
• Remote-site shipping requirements
• Whether a spare battery or backup unit is needed

Using the Trex in Hazardous Areas

An intrinsically safe Trex configuration may be used in applicable classified environments when its approval, installed module, entity parameters and work practices match the site requirement.

However, “intrinsically safe” does not mean the instrument can be taken into every hazardous area without checking the label.

Before use, verify:

• The exact Trex model and module
• Certification markings
• Gas and dust group
• Equipment protection level
• Temperature class
• Ambient-temperature limits
• Connected-device parameters
• Approved leads and accessories
• Site hazardous-area classification

The user guide should be read before operation, and warnings concerning electrical connections, charging and module use must be followed. Emerson specifically requires users to understand the manual before working with the unit.

Battery charging and accessory connection requirements may differ inside and outside hazardous areas. Use only the approved charger and follow the exact certificate and manual supplied with the rental unit.

Where an AMS Trex Rental Can Be Used

Canadian applications may include:

• Oil and gas production
• Refineries
• Chemical processing
• Pulp and paper
• Water and wastewater treatment
• Food and beverage processing
• Power generation
• Mining and mineral processing
• Pharmaceutical manufacturing
• District-energy systems
• Industrial commissioning
• Instrumentation maintenance
• Shutdown and turnaround support

The value is strongest where technicians must work with a mixed population of intelligent devices and need one portable platform for communication, power and loop troubleshooting.

Rental vs Purchase

Renting May Be Better When

• The requirement is temporary.
• The project has a fixed start and end date.
• Additional units are needed for a shutdown.
• The communicator is needed while an owned unit is repaired.
• The team wants to evaluate Power the Loop.
• Catastrophic downtime makes immediate availability more valuable than ownership.
• A specific application or module is needed only occasionally.

Purchasing May Be Better When

• Technicians use the communicator every week.
• The site has a large installed HART or Fieldbus device population.
• The organization needs permanent configuration history.
• Immediate access is critical.
• Calibration-oriented use is frequent.
• Device descriptions and software are actively managed internally.
• The total annual rental cost begins to approach ownership cost.

The purchase decision should include more than the initial instrument cost. Consider support, calibration, application licensing, device-description updates, batteries, repairs, training and fleet management.

Practical Takeaway

An Emerson AMS Trex rental can help instrumentation teams configure, commission and troubleshoot intelligent field devices without assembling a separate collection of communicators, power supplies and loop tools.

Its most useful capability for bench work is Power the Loop, which allows a suitably configured Trex to power an unpowered compatible device directly. With the Plus communication module, the platform can also support 4–20 mA loop diagnostics, current measurement and transmitter simulation.

The rental should be selected by capability, not by product name alone.

Before ordering, confirm:

• Legacy Trex or AMS Trex 2
• HART and/or FOUNDATION Fieldbus capability
• Standard or Plus communication module
• Power the Loop
• Loop Diagnostics
• Required applications
• Device-description compatibility
• Calibration documentation
• Hazardous-area approval
• Included leads and accessories

JM Test Systems Canada can support process and instrumentation teams with AMS Trex rentals, field communicators, loop calibrators, process instruments and related test-equipment services. Availability, exact model and kit contents should be confirmed through the Canadian rental quote.