Comprehensive Product Summary – NuDAM ND‑6521 Addressable Isolated Converter (RS‑232 to RS‑485/RS‑422)

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### 1. Product Overview

Product Name: NuDAM Addressable Isolated Converter RS‑232 to RS‑485/RS‑422
Model Number: ND‑6521
Series: NuDAM‑6000 Series Communication Modules
Article Number: ND‑6521
Manufacturer: ADLINK Technology Inc.

The NuDAM ND‑6521 is an industrial‑grade, addressable communication converter designed to interface RS‑232 devices with RS‑485 or RS‑422 networks. It provides full electrical isolation, configurable addressing, and flexible communication modes, enabling reliable integration of legacy serial equipment into modern multi‑drop industrial networks. The ND‑6521 is part of ADLINK’s NuDAM‑6000 modular data acquisition and communication family, which supports distributed control and monitoring applications across long‑distance serial networks.

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### 2. Key Features

- Bidirectional Signal Conversion: Converts RS‑422/RS‑485 differential signals to RS‑232 single‑ended signals, allowing RS‑232 devices to communicate over extended RS‑485/RS‑422 networks.
- Addressable Operation: Each ND‑6521 can be assigned a unique address (00–FF hex), enabling up to 256 modules to coexist on a single RS‑485 bus.
- Dual‑Mode Functionality: Operates in either addressable or non‑addressable (transparent) mode, selectable via software or hardware configuration.
- High‑Speed Communication: Supports baud rates from 1,200 to 115,200 bps, with independent speed settings for RS‑232 and RS‑485/RS‑422 interfaces.
- Full‑Duplex and Half‑Duplex Support:
- RS‑422: 4‑wire full‑duplex differential transmission.
- RS‑485: 2‑wire half‑duplex with automatic direction flow control.
- Optical Isolation: 2,500 Vrms (typical) isolation between communication ports, protecting host systems from ground loops and electrical surges.
- Surge Protection: Integrated transient voltage suppressors (TVS) and positive temperature coefficient (PTC) protection on all communication lines.
- Watchdog Function: Hardware and software watchdog timers ensure automatic recovery from communication or host failures.
- Flexible Configuration: Baud rate, parity, stop bits, and data bits are software‑configurable; checksum and delimiter options enhance communication integrity.
- Industrial‑Grade Design: ABS enclosure with internal EMI shielding and conformal coating for resistance to humidity, salt spray, and chemical exposure.
- Ease of Installation: Plug‑in screw terminal block for RS‑485/RS‑422 and standard DB‑9 female connector for RS‑232 simplify wiring and maintenance.
- Software Compatibility: Supported by ADLINK’s NuDAM Administration Utility for Windows 3.1/95/98/NT/2000 and DOS environments.
- LED Indicators: Power and data transfer LEDs provide visual status feedback.

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### 3. Technical Specifications

Communication Interfaces:
- RS‑232:
- Connector: 9‑pin D‑sub female
- Signals: TXD, RXD, RTS, CTS
- Configurable baud rate: 1,200 – 115,200 bps
- Data bits: 5, 6, 7, 8
- Stop bits: 1 or 2
- Parity: None, Even, Odd

- RS‑422:
- Differential 4‑wire full‑duplex (TX+, TX–, RX+, RX–)
- Surge protection on all signal pins

- RS‑485:
- Differential 2‑wire half‑duplex (DATA+, DATA–)
- Auto‑direction flow control
- Supports up to 128 devices per bus segment

Isolation Voltage: 1,000 V DC (functional isolation), 2,500 Vrms (typical opto‑isolation)
Transmission Distance: Up to 1,200 m (4,000 ft) over twisted‑pair cable
Power Supply: +10 V DC to +30 V DC unregulated, reverse‑polarity protected
Power Consumption: Approximately 0.75 W
Operating Temperature: –10 °C to +70 °C
Storage Temperature: –25 °C to +80 °C
Case Material: ABS plastic with captive mounting hardware
Dimensions / Weight: Compact DIN‑rail or panel‑mountable module (typical NuDAM form factor ~72 × 118 × 25 mm, < 200 g)
Compliance: CE Class A

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### 4. Functionality

The ND‑6521 functions as a protocol‑transparent converter between RS‑232 and RS‑485/RS‑422 networks. It allows a host system or controller on an RS‑485/RS‑422 bus to communicate with standard RS‑232 devices such as PLCs, sensors, data loggers, or terminals.

Operating Principle:
- The module receives differential signals from the RS‑485/RS‑422 bus, converts them to single‑ended RS‑232 levels, and vice versa.
- In addressable mode, each ND‑6521 responds only to commands containing its unique address, enabling multi‑drop communication with up to 256 modules.
- In non‑addressable (transparent) mode, the converter behaves like a direct RS‑232‑to‑RS‑485 bridge (similar to ND‑6520), passing data without address filtering.
- Automatic direction control ensures proper half‑duplex operation on RS‑485 networks without manual RTS toggling.

Typical Applications:
- Integration of RS‑232‑based instruments into distributed RS‑485 control systems.
- Industrial automation and process monitoring networks.
- Remote data acquisition and telemetry.
- Building and floor automation systems.
- POS and testing systems requiring long‑distance serial communication.

Compatibility:
- Works with other NuDAM modules (ND‑6520, ND‑6510, ND‑6530) and standard RS‑485/RS‑422 devices.
- Compatible with Windows‑based configuration utilities and standard serial communication software (e.g., HyperTerminal).

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### 5. Components & Accessories

Included Components:
- ND‑6521 converter module
- Plug‑in screw terminal block for RS‑485/RS‑422 connection
- DB‑9 female RS‑232 connector
- LED indicators (Power/Data)
- User documentation

Optional Accessories:
- NDP‑243U regulated DC power supply (+24 V DC output)
- RS‑232 cable (DB‑9 male‑to‑female)
- Shielded twisted‑pair communication cable for RS‑485/RS‑422
- DIN‑rail mounting kit

Connectors:
- RS‑232 Port: DB‑9 female (pins: 2 = RXD, 3 = TXD, 7 = RTS, 8 = CTS, 5 = GND)
- RS‑485/RS‑422 Port: 10‑pin screw terminal block
- Pin 1 = DATA+
- Pin 2 = DATA–
- Pin 4 = TX+
- Pin 5 = TX–
- Pin 6 = RX+
- Pin 7 = RX–
- Pin 8 = FGND
- Pin 9 = +VS (+10 V to +30 V DC)
- Pin 10 = GND
- Pin 3 = DEFAULT* (used for factory‑default initialization)

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### 6. Installation & Setup

Requirements:
- Host computer or controller with RS‑485/RS‑422 interface (e.g., ND‑6520 or ND‑6530).
- Power supply: +10 V to +30 V DC.
- Shielded twisted‑pair cable for data lines.
- NuDAM Administration Utility software (for configuration).

Installation Steps:
1. Power Off all devices before wiring.
2. Connect the RS‑485/RS‑422 bus lines (DATA+/DATA– or TX+/TX–/RX+/RX–) to the screw terminal block.
3. Connect the RS‑232 device to the DB‑9 female connector.
4. Wire the power supply to +VS and GND terminals.
5. If configuring a new module, short the DEFAULT* pin to GND during power‑up to enter default mode (Address 00, 9600 bps, RS‑485).
6. Use the NuDAM Administration Utility to assign a unique address, set baud rate, and configure checksum or delimiter options.
7. Remove the DEFAULT* short and power‑cycle the module to apply settings.
8. Verify communication using the utility’s terminal or diagnostic functions.

Mounting Options:
- DIN‑rail mounting (standard NuDAM form factor).
- Panel or wall mounting using captive hardware.

Bus Termination:
- Install 120 Ω ± 2 % termination resistors at both ends of each RS‑485 segment.
- Use shielded cable and connect shields to protective earth at multiple points for EMI reduction.

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### 7. Performance & Capabilities

- Data Rate: 1,200 – 115,200 bps (independent per interface).
- Network Capacity: Up to 128 devices per RS‑485 segment; up to 256 addressable modules with repeaters.
- Transmission Distance: Up to 1,200 m (4,000 ft) per segment.
- Isolation: 1,000 V DC functional, 2,500 Vrms optical.
- Error Protection: Hardware current limiting, thermal shutdown, and surge suppression.
- Watchdog Timer: Host watchdog configurable (100 ms – 25.5 s timeout).
- Command Protocol: ASCII‑based command/response structure with optional checksum.
- Response Time: Determined by baud rate and network load; optimized for low‑latency industrial control.
- Limitations:
- RS‑485 bus limited to 128 nodes without repeaters.
- Requires consistent baud rate and data format across network.
- DEFAULT* pin must not be connected to power source (only to GND or left open).

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### 8. Standards & Compliance

- Electrical Standards:
- EIA/TIA‑232‑E (RS‑232)
- EIA/TIA‑422‑B (RS‑422)
- EIA/TIA‑485‑A (RS‑485)

- Isolation & Safety:
- 2,500 Vrms optical isolation between communication ports.
- Reverse‑polarity and surge protection on power and signal lines.

- Environmental & EMC:
- CE Class A conformity for industrial environments.
- EMI‑shielded ABS enclosure with internal conductive coating.

- Quality & Reliability:
- Conformal‑coated PCB for resistance to humidity and chemical exposure.
- Designed for continuous 24/7 industrial operation.

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### 9. Additional Information

Software Support:
- Operating Systems: DOS, Windows 95/98/NT/2000.
- Utilities: NuDAM Administration Utility for configuration, monitoring, and diagnostics.
- Supported Functions:
- Module search and network mapping.
- Address and baud rate configuration.
- Terminal emulation for direct command testing.
- Batch command execution and logging.
- Firmware version and module information retrieval.

Command Set Overview:
- ASCII‑based commands with leading codes ($, %, &, ~, @).
- Functions include configuration, reading module name/version, soft reset, RTS/CTS control, device ID management, delimiter setting, data pass, and watchdog configuration.
- Example: `$30M<CR>` → returns module name “6521”.

Maintenance & Troubleshooting:
- LED Indicators:
- OFF = No power.
- ON = Receiving power.
- Flashing = Data transmission.
- Preventive Maintenance: Periodically check wiring and terminal tightness; disconnect power before servicing.
- Common Issues:
- No communication → verify baud rate, address, and wiring polarity.
- LED off → check power supply and connections.
- Data errors → ensure proper termination and shielding.

Warranty & Service:
- Warranty Period: 1 year from date of purchase.
- Coverage: Defects in materials and workmanship under normal use.
- Exclusions: Damage from misuse, modification, or operation beyond specifications.
- Service Procedure: Return prepaid with proof of purchase; repair or replacement at manufacturer’s discretion.

Manufacturer Contact:
ADLINK Technology Inc.
Industrial Computing Division
(Refer to official ADLINK documentation for regional service centers.)

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### Summary

The ADLINK NuDAM ND‑6521 is a robust, addressable RS‑485/RS‑422‑to‑RS‑232 converter engineered for industrial communication networks. It bridges legacy RS‑232 devices with modern multi‑drop serial infrastructures, offering high isolation, flexible configuration, and reliable performance in harsh environments. With its comprehensive command set, watchdog protection, and software utilities, the ND‑6521 provides a scalable and maintainable solution for distributed control, monitoring, and automation systems requiring long‑distance serial connectivity.