Product Overview

The Schneider TM3AM6G is a mixed analog input/output expansion module in the Modicon TM3 family. Unlike the TM3AI4 and TM3AI8, which are dedicated analog input modules, the TM3AM6G combines four analog input channels and two analog output channels in one compact unit. This allows a Modicon PLC to acquire process measurements and send analog control signals through the same expansion module.

The module supports both voltage and current signals. Its input and output channels accommodate 0–10 V, -10–10 V, 0–20 mA, and 4–20 mA ranges, making it suitable for applications where field instruments and controlled devices use different analog interfaces.

A typical example is a pump station with pressure transmitters and variable speed drives. The four input channels can collect pressure, flow, or other process measurements, while the two output channels send voltage or current reference signals to external equipment. The PLC processes the incoming values and adjusts its outputs according to the programmed control strategy.

This arrangement is also useful in process machinery where several measurement points must be monitored while one or two actuators receive continuous control references. Instead of installing separate input and output modules, the TM3AM6G handles both signal directions within one I/O position.

The TM3AM6G uses removable spring terminal blocks for electrical connections. Its terminal design is particularly relevant in control cabinets where maintenance personnel prefer spring-clamp wiring rather than screw-terminal connections.

When selecting this module for an existing installation, check the controller compatibility, input and output signal ranges, terminal arrangement, and PLC channel configuration. The TM3AM6G and TM3AM6 share the same basic mixed-I/O functionality, but use different terminal connection methods.

Technical Specifications

Product Features

• Four analog input channels and two analog output channels in one module.
• Supports voltage and current signals on both input and output sides.
• Accepts 0–10 V and -10–10 V analog input signals.
• Accepts 0–20 mA and 4–20 mA analog input signals.
• Provides 0–10 V and -10–10 V voltage outputs.
• Provides 0–20 mA and 4–20 mA current outputs.
• 12-bit resolution or 11 bits plus sign, depending on the selected range.
• Removable spring terminal blocks for field connections.
• 24 V DC rated supply voltage.
• Supports resistive output loads.
• Compatible with Modicon M221, M241, M251, and M262 controllers.
• Supports DIN rail and panel mounting.
• IP20 protection for installation inside electrical control cabinets.

Working Principle

The TM3AM6G handles two different signal operations: acquiring analog measurements from field instruments and generating analog reference signals for external equipment.

Its signal flow can be represented as:

Field Transmitters → TM3AM6G Analog Inputs → Modicon PLC → TM3AM6G Analog Outputs → Controlled Devices

On the input side, four channels receive voltage or current signals from connected instruments. For example, a pressure transmitter may send a 4–20 mA signal representing the pressure inside a pipeline. The module converts this electrical signal into a digital value that the PLC can use in its control program.

On the output side, two channels convert the controller’s digital output values into corresponding analog signals. These outputs can be configured for voltage or current operation, depending on the connected equipment.

Consider a variable-speed pump application. The PLC receives pressure feedback through one of the TM3AM6G input channels. If the measured pressure falls below the required setpoint, the control program can adjust the analog output sent to the drive’s speed reference input. As pump speed changes, the pressure transmitter continues sending updated measurements to the input side.

This creates a continuous feedback process rather than a simple digital start/stop command.

The input and output channels support several standard signal ranges, but the physical wiring and software configuration must match. The output load must also remain within the specified impedance limits. For voltage outputs, the load impedance must be at least 1 kΩ, while current outputs require a load impedance not exceeding 300 Ω.

The module’s conversion timing should be considered when configuring applications that depend on frequent measurement updates and output adjustments. The overall timing includes channel conversion and the controller cycle.

Role in a Modicon TM3 PLC Control Architecture

The TM3AM6G serves as a mixed analog I/O interface within a Modicon TM3 expansion arrangement. Its main advantage is that measurement acquisition and analog command generation can be handled through the same module.

A typical control arrangement is:

Field Sensors → TM3AM6G Inputs → TM3 Expansion Bus → Modicon PLC → TM3AM6G Outputs → Drives / Control Devices

In a closed-loop pressure control application, the input channels collect measurements from the process while an output channel sends the PLC’s control reference to a drive or proportional actuator. This makes the TM3AM6G suitable for machines where analog feedback and analog commands need to operate together.

The two output channels can also be assigned to separate devices, allowing the PLC to control two independent analog references while continuing to monitor up to four input signals.

Industrial Applications

Installation and Maintenance

1. Verify the Module Reference: Confirm that the required module is TM3AM6G. The TM3AM6 uses screw terminals, while the TM3AM6G uses spring terminal connections.
2. Check Controller Compatibility: Verify that the installed Modicon M221, M241, M251, or M262 controller supports the planned TM3 expansion configuration.
3. Identify Input and Output Assignments: Determine which field instruments will use the four input channels and which external devices will receive the two analog outputs.
4. Confirm Signal Ranges: Check whether each connected device uses 0–10 V, -10–10 V, 0–20 mA, or 4–20 mA signals.
5. Verify the Power Supply: Check that the external 24 V DC supply remains within the specified 20.4–28.8 V range.
6. Inspect Spring Terminal Connections: Ensure that conductors are correctly inserted and securely held by the spring-clamp terminals.
7. Use Suitable Signal Cables: Use twisted shielded-pair cables for analog circuits and keep the cable length within the specified 30 m limit.
8. Check Output Load Impedance: Confirm that voltage output loads are at least 1 kΩ and current output loads do not exceed 300 Ω.
9. Configure Each Channel: Set the correct input or output mode in EcoStruxure Machine Expert and verify that the software configuration matches the actual wiring.
10. Test Analog Inputs: Compare the PLC measurement values with the connected transmitters’ expected outputs to identify wiring, scaling, or calibration problems.
11. Verify Analog Outputs: Measure the output voltage or current under operating conditions and confirm that the connected drive or actuator responds to the commanded reference.
12. Document Channel Assignments: Record the connected instruments, output devices, signal ranges, and PLC addresses to simplify future troubleshooting and module replacement.

Related Components

Recommended Related Models

Key Advantages

• Combines four analog inputs and two analog outputs in one expansion module.
• Handles both process measurement and analog command signals.
• Supports standard industrial voltage and current ranges.
• Allows different analog signal types within the same I/O arrangement.
• Spring terminal connections simplify field wiring.
• Compatible with several Modicon PLC controller families.
• Supports variable-speed drive and proportional actuator control.
• Reduces the need for separate analog input and output expansion modules.

Technical FAQs

Can the TM3AM6G receive analog signals and control external devices simultaneously?

Yes. The module has four analog input channels and two analog output channels. The inputs collect measurements from field instruments, while the outputs generate voltage or current references for external equipment. Both functions can operate within the same PLC application.

Can the two analog outputs be configured independently?

The module supports voltage and current output ranges, including 0–10 V, -10–10 V, 0–20 mA, and 4–20 mA. The required output configuration must match the connected device and the physical wiring. The PLC program must also use the corresponding output channel settings.

What is the difference between TM3AM6 and TM3AM6G?

Both modules provide four analog inputs and two analog outputs with the same general signal ranges. The main difference is the terminal connection method. TM3AM6 uses removable screw terminal blocks, whereas TM3AM6G uses removable spring terminal blocks. This distinction should be considered when replacing a module in an existing control cabinet.

Can the TM3AM6G directly control a variable-speed drive?

Yes. One of its analog output channels can generate a voltage or current reference for a compatible drive. For example, a 0–10 V signal can be used as a speed reference when the drive is configured for that input type. The PLC can use the module’s analog input channels to acquire process feedback and adjust the output reference according to the programmed control logic.