PXI-8433/4 4-Port Isolated RS485/RS422 Interface
The PXI-8433/4 is a four-port isolated RS485 and RS422 serial interface module for PXI systems. It is designed for high-speed, long-distance and electrically robust communication with industrial devices, controllers and distributed instrumentation.
Each port supports communication rates up to 3 Mbps and provides isolation from the host system and other serial ports. The RS485/RS422 architecture offers differential signaling with better noise immunity than conventional single-ended RS232 communication.
Key Features of the PXI-8433/4
- Four independent isolated serial ports
- RS485 and RS422 communication support
- Maximum transfer rate up to 3 Mbps
- Port-to-port electrical isolation
- Port-to-computer isolation
- 128-byte transmit and receive FIFOs
- DMA-based serial data transfers
- Four 10-position modular connectors
- Supports two-wire and four-wire communication modes
- Suitable for multipoint RS485 networks
- Standard COM-port and NI-VISA access
- NI-Serial software support
PXI-8433/4 Technical Specifications
| Product Model | PXI-8433/4 |
|---|---|
| Part Number | 779539-01 |
| Product Type | Isolated PXI serial interface |
| Supported Standards | RS485 and RS422 |
| Number of Ports | 4 |
| Maximum Baud Rate | 3 Mbps |
| FIFO Size | 128 bytes |
| Isolation Type | Port-to-port and port-to-host isolation |
| Communication Modes | RS422 full duplex and RS485 two-wire or four-wire operation |
| Front Connectors | 4 × 10-position modular jacks |
| RS422 Output Voltage Range | Approximately ±7 V maximum range |
| RS485 Common-Mode Range | Approximately -7 V to +12 V |
| Operating Temperature | 0°C to 55°C |
| Storage Temperature | -20°C to 70°C |
| Dimensions | 100 mm × 160 mm, 3U |
| Module Width | One PXI slot |
PXI-8433/4 Part Number and Accessories
| Item | Part Number | Description |
|---|---|---|
| PXI-8433/4 | 779539-01 | Four-port isolated RS485/RS422 PXI interface |
| 10P10C Serial Cable | Verify pinout and termination when ordering | Connects an individual modular port to the RS485 or RS422 network |
RS422 Full-Duplex Communication
RS422 normally uses separate differential pairs for transmitting and receiving data. This full-duplex arrangement allows simultaneous communication in both directions between the PXI module and a compatible device.
RS422 is commonly used for point-to-point or multidrop communication where greater cable length and noise immunity are required.
RS485 Multipoint Networks
RS485 supports multiple transceivers on a shared differential bus. The PXI-8433/4 can be used as the master or another participating device in compatible two-wire or four-wire networks.
Correct termination and biasing are critical. Termination resistors are normally installed at the physical ends of the bus rather than at every node.
Isolation for Industrial Installations
Each PXI-8433/4 port is isolated from the host and other ports. This helps protect communication when devices are distributed across different cabinets, grounding systems or power domains.
Isolation also helps prevent a problem on one serial network from disrupting other networks connected to the module.
3 Mbps Maximum Baud Rate
The module supports communication rates up to 3 Mbps. Maximum usable cable length normally decreases as the baud rate increases.
Cable impedance, termination, topology, stub length and connected transceivers must all be considered when designing a high-speed RS485 network.
Typical PXI-8433/4 Applications
- Industrial RS485 networks
- RS422 instrument communication
- PLC and motion-control systems
- Distributed sensor networks
- Automotive controller testing
- Aerospace and defense test systems
- Manufacturing automation
- Environmental test equipment
- Multi-drop serial communication
- Long-distance device control
NI-Serial and NI-VISA Integration
NI-Serial presents the four interfaces as standard COM ports. Application software can configure the transceiver mode, baud rate, character format and flow-control behavior.
NI-VISA enables common serial read-and-write functions from LabVIEW, LabWindows/CVI and other supported development environments.
PXI-8433/4 Troubleshooting
No device responds on an RS485 network
Check A/B polarity, termination, biasing and two-wire versus four-wire mode. Different manufacturers may label differential conductors differently.
Only the nearest device communicates
Inspect bus topology, termination placement and cable continuity. Long stubs and star wiring can produce reflections at higher baud rates.
Communication works at low speed only
Reduce cable length, improve termination and use twisted-pair cable with the correct impedance. Check the response time of every connected device.
Received data is echoed unexpectedly
Review the selected transceiver mode and application settings. Some two-wire RS485 configurations can receive the data being transmitted.
One network interferes with another
Verify the isolation and wiring for each port. Ensure that shields, references and cable drains have not created an unintended connection between networks.
PXI-8433/4 vs PXI-8432/4
| Feature | PXI-8433/4 | PXI-8432/4 |
|---|---|---|
| Serial Standard | RS485 and RS422 | RS232 |
| Ports | 4 isolated ports | 4 isolated ports |
| Maximum Baud Rate | 3 Mbps | 1 Mbps |
| Signaling | Differential | Single-ended |
| Best Suited For | Long-distance and multipoint networks | Conventional point-to-point RS232 devices |
Recommended Related Products
- PXI-8433/2 Isolated RS485/RS422 Interface
- PXI-8432/4 Isolated RS232 Interface
- PXI-8431/4 Nonisolated RS485/RS422 Interface
- PXI-8431/2 RS485/RS422 Interface
- PXI-GPIB Instrument Control Module
- View More NI PXI Modules
Frequently Asked Questions
What is the PXI-8433/4?
It is a four-port isolated RS485 and RS422 serial interface for PXI systems.
What is its maximum baud rate?
The maximum supported communication rate is 3 Mbps.
Can it communicate with multiple RS485 devices?
Yes. It can be used in correctly designed multipoint RS485 networks.
Does it support RS422?
Yes. It supports differential RS422 communication as well as RS485 modes.
Does it provide port-to-port isolation?
Yes. Each serial port is isolated from the computer interface and the other ports.
What is the PXI-8433/4 part number?
The NI ordering part number is 779539-01.
Request a Quote for the PXI-8433/4
Contact us for availability and project pricing for the PXI-8433/4 4-Port Isolated RS485/RS422 Interface. We can also help confirm compatible cables, termination requirements and alternative NI serial modules.
