Industrial Serial Communication Solution – Four Star Electronics SC-20 | RS232/TTY Converter
Where This Product Is Used
The Four Star Electronics SC-20 RS232/TTY Communication Converter is deployed across a wide range of industrial and legacy automation environments where RS232 and TTY (20mA current loop) signal conversion is required. Typical application scenarios include:
- PLC & DCS Integration: Bridging legacy TTY-based PLCs (e.g., early Allen-Bradley, Siemens S5 series) to modern RS232 host systems, SCADA platforms, and HMI terminals.
- Industrial Telemetry: Long-distance serial data transmission in process plants, water treatment facilities, and power substations where current loop signaling provides superior noise immunity.
- Legacy Terminal Emulation: Connecting RS232-equipped computers or industrial PCs to TTY-based printers, terminals, and data loggers in manufacturing environments.
- Building Automation Systems (BAS): Interfacing older building management controllers with modern supervisory networks.
- Oil & Gas Field Instrumentation: Reliable serial communication in electrically noisy environments such as pump stations and compressor control panels.
Technical Specifications
- Model: SC-20
- Manufacturer: Four Star Electronics
- Function: RS232 to TTY (20mA Current Loop) Bidirectional Conversion
- Interface A: RS232 (DB9 or terminal block, signal levels ±12V typical)
- Interface B: TTY 20mA Current Loop (active/passive selectable)
- Data Rate: Up to 19,200 bps (application dependent)
- Isolation: Optical isolation between RS232 and TTY sides
- Power Supply: External DC power or loop-powered (model dependent)
- Operating Temperature: 0°C to +60°C (industrial grade)
- Weight: 1,240 g
- Housing: DIN-rail or panel-mount compatible enclosure
Why Engineers Specify This Model
- Proven Legacy Compatibility: The SC-20 is purpose-built to interface with TTY current loop devices that remain in service across thousands of installed industrial sites worldwide.
- Optical Isolation: Galvanic isolation protects both the host RS232 device and the TTY loop from ground loops, transient spikes, and common-mode noise — critical in industrial panel environments.
- Bidirectional Operation: Full-duplex RS232 ↔ TTY conversion supports both transmit and receive paths simultaneously, enabling real-time control and monitoring.
- Compact Form Factor: Fits within standard control cabinet layouts without requiring additional panel space.
- No Driver Required: Transparent to the host OS — appears as a standard serial port, eliminating software integration overhead.
Complete System Bill of Materials
For a complete RS232-to-TTY serial communication retrofit or new installation, engineers typically specify the following alongside the SC-20:
- RS232 serial cable (DB9 male-to-female, shielded, appropriate length)
- TTY current loop cable (twisted-pair, shielded, 20mA rated)
- 24VDC DIN-rail power supply (if active loop power required)
- DIN-rail mounting hardware and terminal blocks
- Surge protection modules for long cable runs (>10m)
- Host PC or PLC with available RS232 COM port (or USB-to-RS232 adapter)
Compliance & Industry Standards
- RS232 interface compliant with EIA/TIA-232-F standard
- TTY 20mA current loop per IEC 60870 and legacy DIN 66020 conventions
- Optical isolation designed to IEC 61010-1 safety requirements
- RoHS compliant (lead-free construction)
- CE marked for European market deployment
Quality Assurance & Sourcing
Konmask.com sources the Four Star Electronics SC-20 directly from authorized distribution channels and verified industrial surplus inventories. Each unit undergoes functional verification prior to dispatch:
- RS232 signal level verification (TX/RX/RTS/CTS)
- TTY loop continuity and current output test
- Isolation resistance check (>1MΩ between RS232 and TTY sides)
- Visual inspection for connector integrity and housing condition
Units are shipped with original manufacturer labeling and documentation where available. Refurbished units are clearly identified and carry a 90-day functional warranty.
How to Source This Part
To place an order or request a quotation for the Four Star Electronics SC-20 RS232/TTY Communication Converter:
- Online: Add to cart directly from this page. Stock is limited — confirm availability before placing bulk orders.
- Email RFQ: Send your BOM or purchase order to support@konmask.com for volume pricing and lead time confirmation.
- Phone/WhatsApp: +0086 19859288691 — available for urgent sourcing inquiries and technical pre-sales questions.
- Lead Time: In-stock units ship within 1–3 business days. Out-of-stock lead time varies by supplier availability (typically 2–6 weeks).
Application-Specific FAQ
Q: Can the SC-20 connect a modern PC (USB/RS232) to an Allen-Bradley PLC-2 or PLC-5 with a TTY port?
A: Yes. Use a USB-to-RS232 adapter on the PC side and connect the SC-20 RS232 port to it. The TTY side connects to the PLC’s current loop port. Ensure the loop current direction (active vs. passive) matches the PLC’s requirement.
Q: What is the maximum cable distance supported on the TTY side?
A: TTY 20mA current loop supports cable runs up to 1,000 meters (3,280 ft) in low-noise environments, significantly exceeding RS232’s 15-meter limit. Use shielded twisted-pair cable for best results.
Q: Is the SC-20 compatible with half-duplex TTY devices?
A: The SC-20 supports full-duplex operation. For half-duplex TTY devices, consult the device’s manual for loop wiring configuration. Contact Konmask technical support for application-specific guidance.
Q: Does the SC-20 require external power?
A: This depends on the loop configuration. Active loop mode requires an external DC power source (typically 12–24VDC). Passive loop mode draws power from the connected TTY device. Verify your system’s loop power architecture before installation.
Q: Can I use the SC-20 in a hazardous area (Zone 1/Zone 2)?
A: The standard SC-20 is not ATEX or IECEx certified. For hazardous area installations, consult Konmask for intrinsically safe or explosion-proof alternatives.
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Contact: support@konmask.com | +0086 19859288691
