Description
ABB CM574-RS – Serial Communication Module for AC500 PLCs
The ABB CM574-RS is a dedicated serial communication module for the AC500 family, designed to add RS‑232/RS‑485 connectivity to PM574-based systems. From my experience, this module is the go-to when you need to pull in data from legacy drives, barcode scanners, weigh scales, or when a compact Modbus RTU network makes more sense than fieldbus over Ethernet. You might notice that it drops right into the AC500 architecture and is configured through ABB Automation Builder, so it usually integrates without fuss.
Company’s Order Placement Process and Guarantees
- Warranty period: 365 days
- Lead time: 1 week for in‑stock items; no more than one month at the latest
- Payment terms: 50% advance payment, full payment before delivery
- Express delivery options: FedEx, UPS, DHL
Key Features
- RS‑232/RS‑485 flexibility – Typically configurable serial channels for point‑to‑point (RS‑232) or multi‑drop (RS‑485) devices.
- Modbus RTU/ASCII support – Commonly used to connect meters, VFDs, HMIs, and instrument clusters with minimal overhead.
- Seamless AC500 integration – Powered from the backplane and engineered to mount alongside the PM574 CPU for a tidy, modular footprint.
- Industrial‑grade performance – Designed for PLC cabinets; stable operation in typical factory temperature ranges and EMI‑heavy environments.
- Easy commissioning – Configurable in ABB Automation Builder; typical baud rates up to 115.2 kbps make retrofits straightforward.
- Space‑saving format – Compact module form factor helps keep enclosure depth and DIN‑rail space under control.
Technical Specifications
| Brand / Model | ABB CM574-RS (AC500 series communication module) |
| HS Code | 8538.90 (Parts for electrical control apparatus, indicative) |
| System Compatibility | AC500 PLC platform, typically used with PM574 CPUs; configured via ABB Automation Builder |
| Power Requirements | 5 V DC via backplane from the CPU/base unit (no separate field supply required in most cases) |
| Serial Interfaces | RS‑232 and/or RS‑485 (configurable); supports Modbus RTU/ASCII and typical baud rates up to 115.2 kbps |
| Signal I/O Types | RS‑232: TX/RX, common handshaking; RS‑485: differential A/B lines (termination typically required at bus ends) |
| Operating Temperature | Typically −25 °C to +55 °C (cabinet installation; derating may apply) |
| Dimensions & Weight | Standard AC500 module format; compact DIN‑rail footprint (approx. 100 × 45 × 70 mm, ~0.2 kg, indicative) |
| Installation Method | DIN‑rail mounting; attaches to the AC500 backplane, typically to the communication‑module position adjacent to the CPU |
Application Fields
This module is often selected when a project needs reliable serial integration without stepping up to a fieldbus gateway. Typical uses include:
- Connecting VFDs and servo drives over Modbus RTU in OEM machinery.
- Collecting readings from weigh scales, analyzers, or barcode/RFID scanners on packaging lines.
- Bridging legacy serial instruments to modern AC500 PLC logic in process skids and utilities.
- Low‑latency point‑to‑point links for operator panels or embedded controllers where Ethernet is unnecessary.
“We added CM574-RS to pull Modbus RTU data from six drives on an existing line. Commissioning took a single shift and the maintenance team liked that we kept the original serial network intact.”
Advantages & Value
- Cost‑effective expansion – Adds serial capability without replacing the CPU or adding an external gateway.
- Reliability in the cabinet – Fewer interconnects and no external power simplify troubleshooting and typically reduce downtime.
- Compatibility – Works within the AC500 ecosystem and with common serial protocols used by drives and instruments.
- Supportability – Configured in ABB’s mainstream toolchain; easier handover for in‑house teams and integrators.
Installation & Maintenance
- Cabinet & mounting – Install on DIN‑rail in a ventilated control cabinet; maintain clearance for airflow around the PLC stack.
- Wiring practices – Use shielded twisted pair for RS‑485; ground the shield at one side to avoid loops; keep serial cables separate from power lines.
- RS‑485 bus rules – Terminate at the two ends and set biasing as required; maintain proper node addressing for Modbus RTU networks.
- Safety – Power down the PLC rack before inserting or removing modules; observe ESD handling procedures.
- Routine care – Periodically check connector tightness, clean dust from vents, and document any firmware updates applied via Automation Builder.
Quality & Certifications
- CE conformity for EMC and Low Voltage (typical for AC500 modules)
- cULus listing for industrial control equipment (region dependent)
- RoHS / REACH compliance
- Manufacturer’s policy: ABB standard factory warranty applies; our coverage is 365 days as stated above
Related/Supporting Components
- ABB PM574 – High‑performance AC500 CPU that pairs naturally with the CM574‑RS for serial expansions.
- ABB SM5xx I/O modules – Digital and analog expansion modules to complete the control system on the same rack.
- ABB CP600 HMI – Operator panels for local monitoring; can coexist with serial networks when Ethernet is reserved for SCADA.
- Shielded serial cabling and RS‑485 terminators – Recommended accessories for stable multi‑drop installations.
One thing I appreciate is how the CM574‑RS keeps serial integration simple: fewer boxes, fewer power supplies, and configuration lives where your PLC logic lives. If your site still has a healthy mix of legacy serial devices, this module typically pays for itself in engineering time alone.
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