Distributed I/O System Selection Guide | BL21x Series Bus Couplers & N Series I/O Modules

Distributed I/O Selection Guide

Distributed I/O Selection Guide

This selection guide covers all BL21x Series distributed I/O couplers (BL210, BL211, BL212, BL214) and compatible N Series I/O modules. Use this page to quickly find the right combination for your industrial automation application, whether you need Modbus TCP, OPC UA, EtherNet/IP, or EtherCAT connectivity.


You are viewing the complete selection guide. To return to a specific product page, please click the corresponding link below:

BL210 Modbus TCP Coupler | BL211 OPC UA Coupler | BL212 EtherNet/IP Coupler | BL214 EtherCAT Coupler

Bus Coupler Selection

Choose the coupler based on your fieldbus protocol requirements. All couplers support up to 32 I/O modules and feature dual Ethernet ports with integrated switch, web-based configuration, and DIN-rail mounting.

BL210 – Modbus TCP Coupler

Protocol: Modbus TCP 

Ideal for integrating legacy serial devices into a Modbus TCP network. Compatible with Siemens, Schneider Electric, Keyence, Codesys, Inovance, Delta, and other Modbus TCP masters.

👉 View BL210 Product Page →

BL211 – OPC UA Coupler

Protocol: OPC UA + Modbus TCP 

Ideal for IIoT and Industry 4.0 applications requiring secure, platform-independent data exchange.

👉 View BL211 Product Page →

BL212 – EtherNet/IP Coupler

Protocol: EtherNet/IP 

Ideal for Rockwell Automation and other EtherNet/IP-based control systems.

👉 View BL212 Product Page →

BL214 – EtherCAT Coupler

Protocol: EtherCAT 

Ideal for high-performance motion control and real-time automation applications.

👉 View BL214 Product Page →


N Series I/O Module Selection Guide

The BL210, BL211, BL212, and BL214 couplers are compatible with all N Series I/O modules listed below. You can mix and match up to 32 modules per coupler.

Digital Input Modules

Model Channels Signal Type
N1161 16 NPN (low level trigger)
N1162 16 PNP (high level trigger)
N1163 16 Dry contact
N1321 32 NPN (low level trigger)
N1322 32 PNP (high level trigger)
N1323 32 Dry contact

Digital Output Modules

Model Channels Signal Type
N2161 16 PNP
N2162 16 NPN
N2321 32 PNP
N2322 32 NPN
N2084 8 Relay output

Analog Input Modules

Model Channels Signal Type
N3081 8 0-20mA / 4-20mA input
N3083 8 0-5V / 0-10V single-ended input
N3046 4 ±5V / ±10V differential input

Analog Output Modules

Model Channels Signal Type
N4081 8 0-20mA / 4-20mA output
N4086 8 ±5V / ±10V output

RTD (Temperature) Input Modules

Model Channels Signal Type
N5041 4 3-wire PT100
N5042 4 3-wire PT1000
N5043 4 4-wire PT100
N5044 4 4-wire PT1000

Thermocouple (TC) Input Module

Model Channels Signal Type
N5088 8 TC (B/E/J/K/N/R/S/T)

Pulse & Mixed Function Modules

Model Channels Function
N9081 8 3-channel pulse counter + 5-channel DI
N9082 8 6-channel pulse output + 2-channel DO
N9083 8 2-channel pulse output (pulse count control) + 4-channel DI + 2-channel DO
N7021 2 When more than 20 IO boards are selected, an additional Power Module is required

Common Technical Specifications (All Couplers)

System Power Supply 24 VDC
System Input current 96mA @ 24VDC
Internal Bus Voltage 5VDC
Current consumption (I/O Modules) Maximum 2000mA@5VDC
Max I/O Modules 32 modules
Ethernet Ports 2 x RJ45 
Ethernet Speed 10/100 Mbit/s
Cable Type Cat 5 STP, max 100m
Wiring Technology Spring-cage connection (tool-free)
Wire Gauge 0.3 – 2.5 mm² (AWG 22-14)
Operating Temperature -20°C to 55°C
Storage Temperature -40°C to 70°C
Relative Humidity 5% – 95% non-condensing
Protection Rating IP20
Mounting DIN-35 rail
Dimensions (W x H x D) 26 x 74.9 x 104.5 mm
Housing Material Polycarbonate, Nylon 6.6

How to Use This Selection Guide

  1. Step 1: Choose your bus coupler based on the fieldbus protocol required by your PLC or control system (Modbus TCP, OPC UA, EtherNet/IP, or EtherCAT).
  2. Step 2: Select the N Series I/O modules you need – digital input/output, analog input/output, RTD, thermocouple, or pulse modules.
  3. Step 3: Combine up to 32 modules per coupler. Mix and match freely.
  4. Step 4: Mount on DIN-35 rail, connect power (24 VDC), and configure via web browser.

Ready to Choose Your I/O System?

After reviewing the selection guide above, click on any coupler below to view detailed product specifications, ordering information, and technical documentation:


Need Help?

For technical support, custom configuration assistance, or volume pricing, please contact Shenzhen Beilai Technology.

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