Industrial 2-Port Serial RS232 to Ethernet Network Device Server ezTCP CSE-H21

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  • Regular price $192.50
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The ezTCP CSE-H21 2-port industrial serial to Ethernet converter is designed for manufacturing and industrial applications that want to quickly and easily add Ethernet connectivity to their system.

The CSE-H21 has two RS232 ports to enable Ethernet network connectivity of your RS232. Not only can you reduce cost and risk, but you can also shorten development time to add the network capability.

Because the CSE-H21 allows you to extend the distance of your serial communication system, you can remotely control and monitor the serial devices over the Internet regardless of distance. With advantages such as stable performance, noise resistance, surge protection circuitry and two electrically isolated RS-232 ports, the CSE-H21 is suitable for many industrial and manufacturing sites.

The CSE-H21 RS232 to Ethernet Network Device Server can be used in diverse applications such as Advertisement and Signage Systems, Remote Weather Monitoring Systems, and Control PLC over Internet.


  • Multi-port RS232 to Ethernet Converter
  • Durable steel case
  • 10/100Base-T Ethernet, auto MDI/MDIX
  • 2 x RS232 (D-SUB 9pin Male, up to 230.4Kbps)
  • Electronically isolated serial ports (noise resistance)
  • Access Restriction: IP and MAC address filtering, Password
  • Security Protocols: SSL3.0/TLS1.0, SSH2.0
  • Flexible configuration and network communication by ‘AT Commands’ (patent)
  • Communication modes (TCP server, TCP client, AT Command, and UDP)
  • Variety of monitoring status (debugging mode, ezManager, Telnet)
  • DHCP and PPPoE
  • DNS (easy access using domain name)
  • DDNS (dynamic IP address management by domain name)
  • IP Change Notification for dynamic IP address management (TCP, UDP and DDNS)
  • Telnet COM Port Control (RFC 2217)
  • Firmware upgrade through Network
  • Powerful management software for Windows OS (ezManager) & Virtual COM Port Redirector for Windows OS (ezVSP)


    • Serial Physical Interface
      • Serial Interface: 2x RS232
      • RXD, TXD, RTS, CTS, GND
      • Electronically Isolated / ±15KV ESD Protection
      • Connector: 2X DB9M Connector
    • Serial Port Properties
      • Baudrate: 300bps ~ 230,400bps
      • Data Bits: 5, 6, 7, 8 bits
      • Parity: None, Even, Odd, Mark, Space
      • Stop Bit: 1, 1.5, 2
      • Flow Control: RTS/CTS (Hardware)
    • Network Interface
      • 10Base-T/100Base-TX Ethernet (RJ45)
      • Ethernet Speed Auto Sense
      • 1:1 or Cross-over Cable Auto Sense
      • 1000 VAC Isolation
      • Surge Protection
    • Software Functions
      • Protocols
        • TCP, UDP, IP ICMP, ARP, Ethernet, TELNET
          TFTP, DHCP, PPPoE, DNS, DDNS
          Telnet COM Port Control Option (RFC 2217)
      • Security
        • SSL (Secure Socket Layer)
        • SSH (Secure Shell)
        • IP & MAC filtering - Restrict host or network
        • Password for Configuring
      • Communication Mode
        • TCP Server (T2S)
        • TCP Client (COD)
        • TCP Server/Client with AT Command (ATC) - Patent
        • UDP Mode (U2S)
      • Additional Functions
        • Remote Debug Function
        • Sending MAC address Option
    • Indicators (LEDs)
      • Power: Red
      • Status: Yellow
      • Ethernet Link: Green
      • Ethernet RXD: Yellow
      • Ethernet TXD: Green
      • COM Ports: TCP Connections, RXD, TXD, CTS, RTS 
    • Management:
      • ezManager: Configuration and Monitoring through Network and Serial
      • TELNET: TELNET Login
      • AT Command: Configuring in ATC Mode - Patent
    • Supplementary Software
      • ezManager: Configuration Tool for Windows through Network and serial
      • ezVSP: Serial to Network Virtual Driver for Windows
      • ezTerm: Simple TCP/IP Communication Test Tool
    • Dimensions
      • Size: 158mm X 90mm X 24mm (6.22 x 3.54 x 0.95 inches)
    • Operating Environments
      • Input Voltage: DC 5±0.5V
      • Current Consumption: 200mA Typical
      • Operating Temperature: -40℃ ~ +70℃
      • Storage Temperature: -40℃ ~ +85℃
    • Certifications
      • KC: Registration(KN 22, KN 24)
      • CE: EMC 2014/30/EU, RoHS 2011/65/EU
      • FCC: FCC Part 15 Subpart B, Class A

 Package includes:

1X CSE-H21 Industrial 2-Port Serial RS232 to Ethernet Network Device Server

Optional Accessories: 

+5V AC/DC Wall Mount Power Supply

MOUNTER and BRACKET Pair for mounting with DIN Rails 

Documentation & Resources:


Industrial 2-Port RS232 to Ethernet Device Server | CSE-H21

ezTCP Serial Networking Introductory video