Product Overview

The Carlo Gavazzi GTU8 is a portable test unit designed specifically for Dupline® modules and networks. As a dedicated diagnostic and monitoring tool for the Dupline fieldbus system, the GTU8 enables field engineers and maintenance technicians to verify bus signal quality, monitor communication status, and ensure overall system stability. The unit is recommended for Dupline system start-up, troubleshooting, and maintenance.

The GTU8 is a bus-powered 128-channel transmitter/receiver unit that can be connected at any point along a Dupline network to monitor or switch channel status. It draws less than 4.0 mA from the signal line, minimizing impact on the bus.

Key Features

• Portable Test Unit – Compact and lightweight design (145 x 90 x 28 mm, 250 g) for convenient field use
• LCD Display – 2 x 16 character LCD with 5 mm dot height for clear status readout
• 12-Key Tactile Keyboard – Dedicated channel keys (1-8) and command keys (MODE, ENTER, scroll up/down) for intuitive operation
• Transmission Latch Function – Enables continuous transmission on selected channels even after releasing the button
• Dual-Group Reading – Simultaneous monitoring of multiple channel groups
• Analog BCD Reading – Monitor values from analog transmitters using the multiplexed 3 1/2-digit BCD format
• Bus-Powered Operation – Powered directly by the Dupline signal line, eliminating the need for external power supplies
• Industrial-Grade Durability – Shock resistant to 15 G (11 ms) and vibration resistant to 2 G (6 to 55 Hz)
• Reverse Polarity Protection – Built-in protection against incorrect connections

Operating Modes

The GTU8 features six distinct operating modes, providing versatile functionality for different diagnostic and control tasks:

1. Digital 1 Group (Digitale Kanalgruppe)
In this mode, the display shows the status of channel group A. Pressing keys 1 through 8 activates the corresponding Dupline channel and transmits it to the bus. The displayed channel group can be changed using the scroll up/down keys.

2. Digital 2 Groups (Digitale Kanalgruppen)
This mode enables the user to select an additional channel group for permanent monitoring on the bottom line of the display.

3. Edit Tx-latch
This mode "latches" the activation of one or more channels. The GTU8 continues transmitting on the selected channel(s) even after the transmission button is released.

4. Analog BCD
Used to monitor values from analog transmitters that utilize the multiplexed 3 1/2-digit BCD format.

5. Split I/O Operation (Split E/A-Betrieb)
A dedicated mode for split input/output operations.

6. Sensor Calibration (Sensorkalibrierung)
Enables sensor calibration functions within the Dupline system.

Technical Specifications

Applications

The GTU8 is a versatile diagnostic tool suitable for a wide range of Dupline fieldbus applications:

• Industrial Automation – Diagnostics and maintenance of Dupline I/O modules, sensors, and actuators on production lines
• Building Automation – Troubleshooting lighting, security, HVAC, and elevator control systems
• Energy Management – Monitoring and testing of Dupline-based energy monitoring and control networks
• Water Distribution – Field testing of irrigation valve control and water management systems
• Mining Operations – On-site diagnostics of Dupline communication networks
• Railway Systems – Testing and maintenance of Dupline-based monitoring and control infrastructure

System Integration

The GTU8 connects to the Dupline network via a 3 mm jack socket. Two cables are included with the unit:

1. GTU8 to Dupline – 3 mm jack plug to 2 mini grips (red for signal, black for common)
2. GTU8 to ASIC module – 3 mm jack plug to 1 6/6 modular plug

The unit can be connected at any point along the Dupline bus line, enabling flexible diagnostics without disrupting network operation.

Installation and Usage Recommendations

• Connect the GTU8 to the Dupline signal line using the provided test cables
• Select the appropriate operating mode using the MODE and ENTER keys
• Use the channel keys (1-8) to activate or monitor specific Dupline channels
• The transmission latch function is useful for continuous signal testing during troubleshooting
• Ensure the unit is stored within the specified temperature range when not in use
• The IP40 protection rating makes the unit suitable for indoor industrial environments