ABB 07 AC 91 GJR5252300R0101 Analog Input/Output Module

The 07 AC 91 is a high-performance, highly flexible analog input/output module within the ABB Advant Controller 31 system family. Designed as a remote module on the CS31 system bus, it facilitates reliable and precise conversion between field analog sensor signals and the control unit's digital signals in industrial automation control systems. With its powerful configuration capabilities, excellent diagnostic functions, and robust design, this module is widely used in various industrial applications such as process control, equipment monitoring, and data acquisition.

The core feature of the module lies in the high configurability of its 16 channels. Users can select between two distinct operating modes via DIP switches on the module, allowing optimal balance between the number of channels, signal type, resolution, and input/output functionality based on actual application needs. It operates on a 24V DC supply voltage and features an electrically isolated CS31 bus interface, ensuring stable system communication and strong noise immunity.

2. Design and Hardware Features

The 07AC91 module employs a compact, modular design with a rugged construction suitable for industrial environments.

1. Appearance and Display: The front panel integrates intuitive display and operating elements, including:

• 8 green channel selection/diagnostic LEDs: Used to indicate the currently selected channel or display diagnostic information (channel number in hexadecimal code).

• 8 green analog value display LEDs: Provide a bar-graph style visual representation of the analog value for the selected channel, enabling quick on-site inspection.

• 1 red error LED: Illuminates when a module error occurs (e.g., measurement out of range).

• 1 test button: Used for manual channel selection, triggering diagnostic display, conducting LED tests, and acknowledging errors.

• The front panel foil contains clear labeling, including address assignments for different operating modes, facilitating installation and commissioning.

2. Electrical Connection and Isolation:

• The module features removable screw-type terminal blocks for easy wiring. The power supply and CS31 bus terminals support conductors up to 2.5 mm² (or two 1.5 mm²). All other analog signal terminals support up to 1.5 mm² conductors.

• Crucial electrical isolation is implemented: The CS31 system bus interface is fully electrically isolated from the rest of the module's internal circuitry. This effectively prevents interference on the bus from affecting analog signal processing and enhances system safety. Additionally, the binary input (terminals 25/26) used to enable the analog outputs is also isolated.

• Important Note: There is no electrical isolation within the module between the internal analog circuitry (including the reference ground AGND for all analog I/O channels) and the power supply (the M terminal of the 24V DC). The maximum permissible potential difference between them is ±1V. Therefore, all connections for external analog signal sensors and actuators must be electrically isolated from their installation environment. Furthermore, cable shields must be connected to the cabinet ground where they enter the control cabinet.

3. Mounting Options: The module offers two flexible mounting options:

• Standard DIN Rail Mounting: Complies with DIN EN 50022-35 standard, suitable for 15mm high DIN rails.

• Direct Screw Mounting: Fixed using four M4 screws.

• The module must be installed vertically with terminals facing up/down. Sufficient space around the module (especially above and below) must be ensured for natural convection cooling, preventing overheating caused by blockage from cable ducts or other components.

3. Core Functions and Operating Modes in Detail

The most prominent feature of the 07AC91 is its dual operating mode design, selectable via position 8 of DIP switch 1.

1. "12-bit" High-Precision Mode:

• Channel Configuration: Fixed as 8 analog inputs (terminals 4-19) and 8 analog outputs (terminals 27-42). Both input and output channels can be individually configured for either ±10V voltage signals or 0...20mA current signals.

• Resolution: Provides high 12-bit resolution. For the ±10V range, this is effectively 11 bits plus a sign bit. For the 0...20mA range, it is 12 bits unsigned.

• Data Representation: In the control system (PLC), each analog value occupies a full word (16 bits). For example, a -10V to +10V input corresponds to a digital range of -32760 to +32760 (hexadecimal 8008 to 7FF8). If the input exceeds the range, the module outputs a fixed overflow value (+32767 or -32767).

• Application: Ideal for applications requiring high measurement and control precision, such as precise temperature or pressure control, or complex systems requiring simultaneous high-precision acquisition and output of multiple channels.

2. "8-bit" High-Density Mode:

• Input or Output.

• 0...10V voltage signal or 0...20mA current signal.

• Channel Configuration: The 16 analog channels (terminals 4-19 and 27-42) are configurable. Using DIP switches, configuration is done in pairs (two channels per group). Each pair can be independently set as:

• Resolution: Provides 8-bit resolution.

• Data Representation: To conserve bus resources, the 8-bit digital values of two channels are "packed" into one 16-bit word (one channel in the low byte, the other in the high byte). For example, 0...10V corresponds to a digital range of 0 to 255 (hexadecimal 00 to FF).

• Application: Suitable for applications where more signal channels are needed with relatively lower precision requirements, such as multi-point temperature monitoring or batch valve control, offering a cost-effective way to expand the system's analog signal handling capacity.

3. Analog Output Enable Function:

• All analog output channels of the module (in either mode) are controlled by a dedicated enable input. This input is located at terminals 25 (+) and 26 (-) and requires a 24V DC signal (binary "1") to activate all analog outputs.

• If the enable signal is not present, all voltage outputs remain at 0V, and current outputs remain at 0mA. This feature adds a layer of safety, allowing all analog outputs to be safely disabled during emergencies or maintenance.

4. Configuration and Addressing

Module address and operating mode configuration are performed entirely via two DIP switches located under a slide cover on the right side of the module, requiring no software tools—simple and reliable.

1. Module Address Setting: Set via the Address DIP switch (8 positions). The address value is the sum of the weights corresponding to all switches in the "ON" position (weights are 1, 2, 4, 8,...). This address determines the module's logical position on the CS31 bus. When used with central units like the 07 KR 91 / 07 KT 9x series, the available address range is typically 00-05 or 08-15.

2. Channel Configuration:

• "12-bit" Mode: Uses DIP switches 1 and 2. Each bit corresponds to one channel (E0-A7). OFF = ±10V, ON = 0...20mA.

• "8-bit" Mode: Uses DIP switches 1 and 2. Every two bits correspond to a channel pair. The left switch determines direction (OFF = Input, ON = Output). The right switch determines type (OFF = 0...10V, ON = 0...20mA).

3. Addressing in the PLC:

• "12-bit" Mode: Each input/output channel occupies its own analog input word (EW) or analog output word (AW). For example, if the base address is 'n', input E0 corresponds to EW n,00, and output A0 corresponds to AW n,00.

• "8-bit" Mode: Each word contains two channels. For example, if the base address is 'n', channel pair 0/1, when configured as inputs, corresponds to the low byte (Lo) and high byte (Hi) of EW n,00.

5. Diagnostic and Maintenance Features

The 07AC91 is equipped with a comprehensive diagnostic system, greatly simplifying troubleshooting and maintenance.

1. Diagnostic Display:

• Module Level: The red error LED illuminates indicating an error.

• System Level: Error information (e.g., "Out of range") is transmitted via the CS31 bus to the central unit. Detailed information such as error classification, module type, group number, and channel number can be viewed in specific PLC status words (e.g., MW 255).

• Channel Level: Using the front panel test button, status can be queried channel by channel. Pressing the button makes the channel selection LEDs display the current channel number in binary code. Releasing the button makes the analog value LEDs show the magnitude of the analog signal for that channel. Subsequently, for about 3 seconds, specific LEDs (e.g., LED 4) lighting up indicate conditions like "Out of range" for that channel.

2. Error Acknowledgment: After a fault is rectified, the error indication can be cleared by acknowledging the error via:

• Pressing and holding the module's test button for about 5 seconds.

• Using the programming software (PC).

• Executing an acknowledgment command in the PLC program of the central unit.

3. Self-Protection Feature (Current Input): When configured for 0...20mA current input and the current exceeds limits, the module's internal input shunt automatically turns off for self-protection and outputs an "overflow" value. The module attempts to reactivate measurement approximately once per second. Once the current returns to an acceptable range, correct measurement resumes.

4. LED Test: The test button can initiate a test where all LEDs illuminate, facilitating a quick check of the display unit's functionality.