Description
Key Technical Specifications
- Model Number: 1SAP220700R0001 CI502
- Manufacturer: ABB Industrial Automation
- Communication Port: 1× RS-485 (half-duplex, 2-wire configuration)
- Protocol Support: Modbus RTU (Master/Slave configurable)
- Data Rate: 1200 bps to 115200 bps (user-selectable)
- Isolation Rating: 1kV AC galvanic isolation (port to PLC backplane)
- Power Supply: 24VDC ±10% (derived from AC500 PLC backplane, 0.08A typical current draw)
- Operating Temperature: -25°C to +60°C (-13°F to +140°F)
- Physical Design: DIN-rail mount, 22.5mm width (compact profile), IP20 protection
- Connection: Screw terminals for RS-485 wiring
- Configuration Software: ABB Automation Builder
- Certifications: CE, UL 508, CSA C22.2 No. 14
ABB 1SAP220700R0001 CI502
Field Application & Problem Solved
In packaging lines, material handling systems, and small-scale process plants, the biggest communication headache is connecting an AC500 PLC to legacy Modbus RTU field devices (e.g., VFDs, temperature controllers, flow meters). Without a dedicated communication module, you’d have to use the PLC’s CPU serial port—this ties up the CPU, slows down scan times, and limits connectivity to one device at a time. I’ve seen a food packaging plant’s CPU scan time double because they used the built-in serial port to poll 8 temperature meters, causing conveyor belt lag and product jams.
You’ll find the CI502 module clipped onto AC500 PLC racks in small to mid-sized automation cells—think beverage bottling lines, warehouse conveyor systems, and water treatment skids. It’s a low-cost, compact solution for multi-device Modbus networks, and its galvanic isolation makes it ideal for noisy factory floors. Its core value is offloading serial communication tasks from the PLC CPU: the module handles all Modbus polling, freeing the CPU to focus on control logic. At a Georgia water treatment plant, adding CI502 modules cut PLC scan time by 40% and eliminated conveyor lag entirely—all while connecting 12 flow meters to the system.
Another critical value is its Master/Slave flexibility. You can configure it as a Master to poll field devices, or as a Slave to let a SCADA system read PLC data—no need for separate modules for each role. This is a game-changer for small plants that can’t afford dedicated gateways for monitoring and control.
Installation & Maintenance Pitfalls (Expert Tips)
- Termination Resistors Are Non-Negotiable: The RS-485 port requires a 120-ohm termination resistor at the first and last devices on the network. Rookies either skip the resistors or install them on every device, causing signal reflection and communication timeouts. Check the module’s dip switch (if equipped) or enable termination in software—this fixes 90% of Modbus communication faults. I’ve fixed a Michigan packaging plant’s network by adding two termination resistors; they’d been troubleshooting for 3 days.
- Grounding the RS-485 Shield Correctly: The RS-485 cable shield must be grounded at one end only (preferably the module end). Grounding both ends creates ground loops that introduce noise, leading to corrupted data and “bad CRC” errors. Use a shielded twisted-pair cable, strip the shield back 1 inch, and connect it to the module’s ground terminal—leave the field device end ungrounded. A Tennessee automotive parts plant eliminated false VFD speed readings by fixing their shield grounding.
- Matching Baud Rate & Parity Exactly: Mismatched communication parameters (baud rate, parity, stop bits) between the module and field devices are the #1 cause of “no communication” faults. Don’t assume default settings work—cross-verify every parameter in Automation Builder and on the field device. For example, if the module is set to 9600 bps/8-N-1, the VFD must match exactly. I spent 2 hours troubleshooting a South Carolina plant’s system because the module was set to even parity while the meters used odd parity.
- Avoid Daisy-Chaining Power & Signal Cables: Technicians often run RS-485 signal cables alongside 24VDC power cables to save time. This introduces EMI from power cables, causing intermittent communication drops. Route signal and power cables in separate conduits or trunking, with at least 10cm of separation. A Florida plastics plant reduced communication faults by 75% just by separating their cables.
ABB 1SAP220700R0001 CI502
Technical Deep Dive & Overview
The ABB 1SAP220700R0001 CI502 is a compact RS-485 communication module designed for AC500 PLCs, built to handle Modbus RTU traffic in industrial environments. At its core, a dedicated microcontroller manages all serial communication tasks—this is what offloads work from the PLC CPU and keeps scan times fast. The module converts Modbus RTU signals to the AC500 backplane protocol, enabling seamless data exchange between the PLC and field devices.
Its galvanic isolation uses optocouplers to separate the RS-485 port from the PLC backplane, blocking voltage spikes and ground loops that would otherwise damage the module or corrupt data. The half-duplex RS-485 port supports up to 32 devices on a single network, with a maximum cable length of 1200 meters (3937 feet)—plenty for most factory floors.
Configuration is done via ABB Automation Builder software, where you set the module as Master or Slave, define communication parameters, and map Modbus registers to PLC memory addresses. The module’s compact 22.5mm width saves rack space, allowing you to fit multiple CI502 modules alongside I/O modules for large networks. Built with industrial-grade components and a rugged DIN-rail mount, it’s rated for 10+ years of operation in harsh factory environments—making it a reliable, cost-effective solution for PLC-to-field device communication.
