You've selected the ABB SAFT181INF expansion interface board for your project. The hardware is on the workbench. Now comes the critical phase: turning that piece of hardware into a functioning node on your INFIBUS network. A successful installation hinges on meticulous planning, precise configuration, and systematic testing. This guide walks through the practical steps, from unpacking the board to diagnosing common issues, providing a roadmap for technicians and engineers.
Phase 1: Pre-Installation Planning and Safety
Before touching any hardware, a plan is essential. Always adhere to local electrical codes and lockout/tagout (LOTO) procedures. De-energize all power supplies.
- Review Documentation: Locate the hardware manual for the exact SAFT181INF variant you have. This is your primary reference for DIP switch functions, terminal layouts, and specifications.
- Network Design: Sketch your INFIBUS network topology. Determine the order of stations (master -> slave 1 -> slave 2, etc.). Assign a unique station address to each SAFT181INF on the network. The address range and setting method (typically rotary switches or DIP switches on the board) are in the manual. Document this addressing scheme.
- Cable and Termination Plan: Use proper shielded, twisted-pair INFIBUS cable. Plan the cable run, avoiding parallel runs with high-voltage power lines. The INFIBUS segment must be terminated at both physical ends with a 220-ohm resistor. Identify which stations will be the ends. Many SAFT181INF boards have a built-in terminating resistor that can be enabled with a jumper; otherwise, an external terminator plug is needed.
Phase 2: Physical Installation and Wiring
- Rack and Power: Mount the expansion rack securely. Install a suitably rated power supply unit (PSU) for the rack, ensuring it can handle the total current draw of all modules.
- Insert the SAFT181INF: Install the board into slot X1 (the first slot) of the expansion rack. It must be in this slot to function as the head module. Push firmly until it clicks into the backplane connector.
- Set the Station Address: Using the documented plan, set the rotary or DIP switches on the SAFT181INF to its assigned unique address. Double-check this setting.
- Configure Termination: If this station is at either end of the INFIBUS trunk, enable the termination resistor via the on-board jumper as per the manual. For intermediate stations, ensure termination is disabled.
- INFIBUS Wiring: Connect the INFIBUS cable to the board's terminals (often labeled "IN" and "OUT" or "A" and "B"). Ensure polarity is consistent across the entire network (A to A, B to B). Secure the cable shield to the functional earth (FE) rail in the cabinet, typically at one end only to prevent ground loops.
- Install I/O Modules: Populate the remaining slots in the rack with the required S500 I/O modules (DIs, DOs, AIs, etc.).
Phase 3: Software Configuration in Engineering Tool
The physical board must be declared in your PLC programming software (e.g., ABB's Automation Builder).
- Hardware Configuration: In your project, navigate to the hardware configuration of the AC 500 PLC station.
- Add INFIBUS Network: Locate and add the INFIBUS master module (e.g., the IA INF card in the main PLC rack) to the configuration.
- Add Slave Station: Under the INFIBUS master, add a new slave device. Select the correct device type/profile that matches your SAFT181INF (the GSD or HSP file may need to be imported).
- Assign Parameters: Set the slave's PROFIBUS/INFIBUS address to match the hardware address you set on the DIP switches. The software will often allow you to configure the expected I/O data layout (the input and output bytes that will be exchanged with this remote station).
- Map I/O: The configuration tool will automatically or manually create a process image for the remote station. You will map the I/O points from the modules in the SAFT181INF's rack to variables in your PLC program.
Phase 4: Commissioning and Troubleshooting
- Power Up: Apply power to the main rack and then the expansion rack.
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LED Diagnostics: Observe the LEDs on the SAFT181INF. A steady green on the "COM" or "BF" LED usually indicates successful communication with the master. A red or flashing light indicates a fault. Consult the manual's LED status chart.
- Online Test: Go online with the PLC from your engineering software. Check the diagnostics of the INFIBUS master module. It should report the SAFT181INF station as "OK" or "Good."
- I/O Loop Check: This is crucial. Manually activate a field device connected to a digital input on the remote rack. Verify the status change appears in the PLC's input variable table. Command a digital output from the PLC and confirm the field device activates.
Common Issues and Solutions:
- Station Not Found (Flashing Red LED):
- Cause 1: Address mismatch between hardware (DIP switch) and software configuration.
- Fix: Verify and correct the address in the hardware or software.
- Cause 2: Incorrect network termination or cable break.
- Fix: Check continuity of INFIBUS cable. Verify terminators are enabled at both ends only.
- Intermittent Communication:
- Cause: Electrical noise or faulty connectors.
- Fix: Ensure proper shield grounding. Check and reseat all INFIBUS connectors. Inspect cable for damage.
- I/O Data Incorrect/Missing:
- Cause: I/O module mapping in software does not match physical module order in the remote rack.
- Fix: Reconcile the hardware configuration in the software with the actual module lineup in the expansion rack.
By following this structured approach—plan, install, configure, test—you can reliably integrate the ABB SAFT181INF into your control system. Remember, careful attention to addressing, termination, and software-hardware consistency is the key to a trouble-free startup.
