Key Technical Specifications

• EtherNet/IP Connections: 2 Class 1 I/O, 5 Class 3 Server, 3 Class 3 Client
• Supported PLC Types: PLC2, PLC5, SLC, ControlLogix, CompactLogix
• Message Types Supported: PCCC and CIP
• I/O Connection Size: 248 bytes input / 248 bytes output
• Max RPI Time: 5 ms per connection
• Serial Buffer Size: 255 bytes send/receive
• Send Character Delay: 0 to 65535 ms
• Power Supply: 24 VDC nominal (10 to 36 VDC allowable)
• Current Load: 300 mA @ 24 VDC nominal
• Operating Temperature: -25°C to 70°C (-13°F to 158°F)
• Dimensions (H x W x D): 5.38 x 1.99 x 4.38 in (13.67 x 5.05 x 11.13 cm)

 

Product Introduction

The ProSoft PLX31-EIP-ASCII is a dedicated communication gateway designed to bridge EtherNet/IP PACs and serial ASCII devices. It enables high-speed, bidirectional data exchange between modern Ethernet-based controllers and legacy serial equipment like barcode scanners and industrial scales.Field integrators value this module for its deterministic timing and straightforward configuration. With a maximum RPI of 5 ms and a 248-byte I/O connection size, the PLX31-EIP-ASCII handles rapid polling cycles without saturating the network. (I’ve seen this exact setup reliably poll a 20-station packaging line at 10 ms RPIs without dropping packets.)

Installation & Configuration Guide

Preparation: Power down the EtherNet/IP backplane. Verify your 24 VDC supply reads between 21.6 V and 26.4 V under load. Download the embedded EDS file from the SD card or ProSoft website to your RSLogix/Studio 5000 project.Removal: If replacing an existing module, document the IP address and DIP switch settings. Remove the Ethernet and serial cables. Release the backplane latch and slide the module out.Installation: Insert the PLX31-EIP-ASCII into the designated rack slot. Engage the backplane connector firmly. Reconnect the Ethernet cable to the 100 Mbit port. Wire the serial port (RX, TX, GND) to your ASCII device.Power-On & Test: Apply backplane power. Watch the PWR, NS, and MS LEDs. The NS LED should flash green when an EtherNet/IP connection is established. Use the ProSoft Discovery Service utility to verify the module’s IP address if it is on a different subnet.

 

Troubleshooting Quick Reference

• Symptom: NS LED solid red. Probable Cause: Duplicate IP address or no physical link. Action: Ping the module. Check Ethernet cable continuity.
• Symptom: MS LED flashing red. Probable Cause: Configuration mismatch. Action: Verify EDS file version matches firmware. Check RPI settings.
• Symptom: Serial RX LED off during expected traffic. Probable Cause: Wiring error or baud rate mismatch. Action: Measure voltage on TX pin from the ASCII device. Verify serial parameters.
• Symptom: Intermittent data drops. Probable Cause: Ground loop or ESD. Action: Ensure single-point grounding. Check serial cable shielding.
• Symptom: Module won’t accept configuration. Probable Cause: Corrupt SD card or write-protect switch. Action: Replace SD card. Toggle write-protect.

Dimensions, Mounting & Wiring Notes

Mounting: Standard 1756-series backplane slot. Single-slot width.
Dimensions: 5.38 x 1.99 x 4.38 inches (13.67 x 5.05 x 11.13 cm).
Wiring Notes: Use shielded twisted-pair cable for serial connections. Terminate the shield at the gateway end only to prevent ground loops. The module includes dedicated RX and TX LED indicators for real-time serial traffic verification. (A burnt smell near the serial port usually means a shorted 24 VDC wire touched the signal pins—always double-check before applying power.)

 

FAQ

Why won’t my ControlLogix see the PLX31-EIP-ASCII in the I/O tree?
Check the module slot configuration in Studio 5000. The catalog number must match exactly. Also, verify the EDS file is properly installed in the RSLinx EDS repository.I need to poll three scales at once. Can I do that with this module?
Yes. The PLX31-EIP-ASCII supports multiple Class 1 I/O connections. You can configure separate RPIs for each device to prioritize critical traffic.How do I find the module if I don’t know its IP address?
Use the ProSoft Discovery Service utility. It broadcasts across subnets and displays the module’s MAC address and current IP. No router configuration needed.What’s the max serial cable length I can run?
RS-232 is limited to 50 feet. For longer runs, use an RS-422/485 transceiver. The module supports both.Is this module still manufactured?
ProSoft periodically updates their product lines. Check their official website for current production status. New Surplus units are available and fully tested.Can I configure this as a server instead of a client?
Yes. The module supports both client and server modes. Server mode is useful when multiple PLCs need to read data from the same ASCII device.