Milestone Electronics
Model: LDA-1044UDP
RS422/RS485 to 4 RS232 & 4 RS422/RS485 Converter Splitter
The LDA-1044UDP accepts a single RS485 or RS422 input and simultaneously distributes it to four RS485/RS422 outputs and four RS232 outputs. Designed for high-speed data transmission over long distances under high noise conditions, with opto-isolation and transient protection on every output port.
- Single RS485/RS422 input split to 4 RS485/RS422 and 4 RS232 outputs simultaneously
- Each RS485/RS422 output individually opto-isolated with spike suppressor protection
- Maximum transmission distance of 1.2 km at 19,200 bps over RS485/RS422
- 2500 V peak transient protection across all output ports
- Mains powered with built-in 230 V, 50 Hz power supply
Max Resolution
1080p Full HD
Audio Input
Stereo Analogue
Output
Single HDMI
- In-house manufactured
- 24hr response
- 2,000+ clients served
Product Overview
What the LDA-1044UDP delivers
The Milestone LDA-1044UDP is an RS485/RS422 to RS485/RS422/RS232 converter-splitter engineered for high-speed serial data distribution in demanding industrial environments. It accepts a single RS485 or RS422 input and fans it out simultaneously to four RS485/RS422 outputs and four RS232 outputs, enabling one data source to communicate with multiple devices across different interface standards without additional converters.
Each RS485/RS422 output port is individually protected by a spike suppressor and opto-isolation circuit. This dual-layer protection ensures that electrical transients or ground potential differences between connected equipment do not propagate through the system, maintaining data integrity across all output lines simultaneously. Transient protection is rated at 2500 V peak, making the unit suitable for electrically noisy industrial installations.
For RS485/RS422 connections, the unit supports cable runs of up to 1.2 km at 19,200 bps using twisted pair shielded cable. The RS422/RS485 ports use D9 Male connectors with the positive and negative differential signal pair on pins 5 and 6 respectively. The four RS232 output ports use D9 Male connectors with Tx on pin 3, Rx on pin 2, and GND on pin 5.
Front panel LED indicators provide real-time status visibility. The Power LED confirms that mains power is present, while the TD LED indicates active data transmission on both the RS485 and RS232 lines. The unit operates from a 230 V, 50 Hz mains supply with a built-in power supply rated at a maximum of 50 VA.
Input
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Key Features
Industrial-grade serial signal distribution
One RS485/RS422 input simultaneously distributed to eight output ports across two interface standards, with per-port isolation and high noise immunity for long-distance industrial deployments.
Dual Interface Output: 4 RS485 and 4 RS232
A single RS485/RS422 input is simultaneously fanned out to four RS485/RS422 outputs and four RS232 outputs. This allows one data source to interface with multiple devices using different serial standards without requiring separate conversion hardware for each port.
- 4 RS485/RS422 outputs on D9 Male connectors with differential signal pairs
- 4 RS232 outputs on D9 Male connectors with Tx, Rx, and GND
- All outputs active simultaneously from a single input source
Per-Port Opto-Isolation and Spike Suppression
Each RS485/RS422 output port is individually protected by both a spike suppressor and an opto-isolation circuit. This isolates connected devices from ground loops, electrical transients, and high common mode noise that is common in factory and industrial environments.
- Opto-isolation on every RS485/RS422 output port
- Spike suppressor on every RS485/RS422 output port
- Prevents fault propagation between connected equipment
Long Distance Transmission up to 1.2 km
The RS485/RS422 outputs support cable runs up to 1.2 km at 19,200 bps. The differential signalling of RS485/RS422 provides inherent common mode noise rejection, making the unit reliable for remote data transmission over long distances in electrically noisy industrial facilities.
- Maximum distance of 1.2 km at 19,200 bps
- Twisted pair shielded cable required, rated up to 90 ohms per 1000 metres
- High common mode noise rejection via differential signalling
2500 V Peak Transient Protection
All output ports are protected against transient voltage spikes rated at 2500 V peak. This level of protection is essential in industrial installations where switching equipment, motors, and power cables can induce high-voltage transients on signal lines, potentially damaging connected instrumentation.
- 2500 V peak transient protection across output ports
- Protects connected peripherals and control equipment
- Suitable for electrically noisy factory and industrial environments
Front Panel LED Status Indicators
Two front panel LEDs provide immediate operational status without requiring additional diagnostic tools. The Power LED confirms mains supply is active. The TD LED indicates data transmission activity across both the RS485 and RS232 output lines, allowing technicians to quickly verify signal flow during installation and fault finding.
- Power LED indicates unit is receiving mains supply
- TD LED indicates active data transmission on RS485 and RS232 lines
- Visible front panel indicators for quick status verification
Built-In Mains Power Supply
The LDA-1044UDP includes a built-in power supply accepting 230 V, 50 Hz mains input, rated at a maximum of 50 VA. This eliminates the need for an external power adaptor and simplifies installation in control panels and equipment enclosures where mains power is readily available.
- Mains input of 230 V, 50 Hz built in
- Maximum power consumption of 50 VA
- No external power adaptor required
Installation
Connecting input, outputs, and cabling
The LDA-1044UDP connects a single RS485/RS422 source to up to eight output devices. Correct connector pinout and cable selection are essential for reliable long-distance operation.
01
RS422/RS485 Input and Output Connections
Connect the RS485/RS422 source to the Male D9 input connector using pins 5 (+Tx/Rx-B) and 6 (-Tx/Rx-A) with pin 7 for GND. Each of the four RS485/RS422 output ports uses the same pinout. Ensure the twisted pair shielded cable is used for each differential signal pair to maintain noise rejection. Cable resistance must not exceed 90 ohms per 1000 metres.
02
RS232 Output Connections and Cable Routing
Each of the four RS232 output ports uses a D9 Male connector with Rx on pin 2, Tx on pin 3, and GND on pin 5. When routing long-distance cables for RS485/RS422 outputs, do not run the signal cable parallel to power line cables, as this can induce noise. Route cables through conduit pipe for physical protection and connect the shield at one end only to avoid ground loops.
03
Long Distance Cable Laying
For distances up to 1.2 km on RS485/RS422 outputs, use twisted pair shielded cable with a characteristic impedance of 90 ohms per km. Each differential pair (+Tx and -Tx) must be carried on the same twisted pair to preserve common mode noise rejection. Avoid parallel runs with 230 V mains wiring and route signal cables through conduit or trunking wherever possible.
04
Power Connection and LED Verification
Connect the unit to a 230 V, 50 Hz mains supply. After power-on, verify that the Power LED on the front panel illuminates to confirm the internal power supply is operational. When data is being transmitted, the TD LED should also illuminate. If the TD LED does not activate during expected data traffic, verify the input signal source and cable connections before proceeding.
Where the LDA-1044UDP performs
Designed for industrial and commercial environments where a single RS485/RS422 data source must communicate with multiple devices over both RS485 and RS232 interfaces, often across long distances and under high electrical noise conditions.
Factory Automation
Connect a single RS485/RS422 control bus from a central PLC to multiple machine controllers, actuators, and monitoring points simultaneously. The opto-isolated outputs protect the master controller from ground differences common between factory floor machines.
Programmable Logic Controllers
Distribute a PLC's RS485 output to multiple remote I/O modules, operator panels, and data logging devices. The multi-port architecture eliminates the need for a separate converter at each slave device and keeps the installation compact.
Attendance Recording Systems
Fan out a single RS485 master signal from a time and attendance server to multiple reader terminals installed at entry and exit points across a facility. The 1.2 km range supports large site deployments with terminals at considerable distances from the central server.
Barcode Reader Networks
Connect a host system's RS485 output to multiple barcode scanners on a production line or warehouse floor. The RS232 output ports also allow legacy scanners to be included in the same installation without additional interface hardware.
Remote Data Transmission and Terminals
Used in remote terminal networks where a central host must simultaneously deliver data to multiple remote data collection units or display terminals over distances up to 1.2 km. The high transient protection ensures data integrity in environments with long cable runs exposed to interference.
EPABX and Telephony Systems
Distribute serial control data from EPABX systems to multiple peripheral units or maintenance terminals. The mixed RS485 and RS232 output capability accommodates the range of interface standards encountered in telephony management equipment without additional converters.
Full specification sheet
- Input
- RS485/RS422 Outputs
- RS232 Outputs
- Protection
- Indicators
- Power Supply
FAQs about the LD-1044UD
What does the LDA-1044UDP do?
The LDA-1044UDP is an RS485/RS422 to RS485/RS422/RS232 converter-splitter. It accepts a single RS485 or RS422 input and distributes it simultaneously to four RS485/RS422 output ports and four RS232 output ports. This allows one data source to communicate with up to eight devices across two different serial interface standards without requiring separate conversion hardware at each point.
What is the maximum cable distance supported on the RS485/RS422 outputs?
The RS485/RS422 outputs support a maximum cable distance of 1.2 km at a baud rate of 19,200 bps. This requires twisted pair shielded cable with a resistance rating of no more than 90 ohms per 1000 metres. The cable should be routed through conduit pipe for physical protection and must not be laid parallel to mains power cables, as this can induce noise on the signal lines.
Are the RS485/RS422 output ports isolated from each other?
Yes. Each RS485/RS422 output port is individually protected by both a spike suppressor and an opto-isolation circuit. This means that ground potential differences, electrical transients, or fault conditions at any one output port do not affect the other ports or the input signal. This isolation is particularly important in factory environments where different machines may have separate earth references.
What connector type and pinout are used on the RS232 output ports?
The four RS232 output ports each use a D9 Male connector. The pin assignment is: pin 2 for Rx (input to the connected device), pin 3 for Tx (output from the LDA-1044UDP), and pin 5 for GND. For the RS422/RS485 input and RS485 output ports, pin 5 carries +Tx/Rx-B, pin 6 carries -Tx/Rx-A, and pin 7 is GND.
What applications is the LDA-1044UDP suited for?
The LDA-1044UDP is designed for industrial and commercial environments where a single RS485/RS422 source must communicate with multiple devices. Typical applications include factory automation, programmable logic controllers, attendance recording systems, barcode reader networks, remote data transmission, remote terminal installations, and EPABX systems. The long-distance capability and high noise immunity make it particularly suitable for large industrial sites.
What type of cable should be used for the RS485/RS422 output connections?
A twisted pair shielded cable must be used for all RS485/RS422 output connections. Each differential signal pair, meaning the positive and negative signal conductors, must be carried on the same twisted pair. This configuration provides high common mode noise rejection. The cable impedance must not exceed 90 ohms per 1000 metres. Signal cables should not be routed parallel to mains power cables and should be run through conduit pipe where possible for physical protection.
Does the unit require an external power supply?
No. The LDA-1044UDP includes a built-in power supply that accepts a standard 230 V, 50 Hz mains input. The maximum power consumption is 50 VA. No external adaptor or separate power unit is required. Simply connect the unit directly to a mains supply. After power-on, the front panel Power LED should illuminate to confirm the internal supply is operating correctly.
What does the TD indicator on the front panel signify?
The TD LED on the front panel indicates active data transmission. It illuminates when data is being sent across both the RS485/RS422 and RS232 output lines. This indicator is useful during installation and fault finding, as it allows a technician to confirm that data is flowing from the input through to the output ports without requiring additional test equipment on every line.
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