NL201 Network Link Interface
Serial to Ethernet Interface
Very low power
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The NL201 is a serial-to-Ethernet interface that provides a wired Ethernet network connection to dataloggers, peripherals, and other serial devices. The NL201 supports sophisticated networking capabilities for PakBus devices and networks. Using a unique technique to bridge the Ethernet and CS I/O ports, the NL201 can provide direct access to the integrated IP functionality of some Campbell Scientific dataloggers. The NL201 can also act as a standard TCP serial server, serial client, Modbus TCP/IP gateway, and TLS proxy server for HTTPS and user-defined-port communication.

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Benefits and Features

  • Integrated protection for surge and ESD


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Detailed Description

The NL201 connects to an Ethernet network using a 10Base-T/100Base-TX, full or half duplex, Ethernet interface. It has CS I/O and RS-232 ports for connecting a Campbell Scientific datalogger, peripheral, Modbus RTU, or other serial based device. A USB micro B connection is provided for on-site configuration using Device Configuration Utility software.

The NL201 can act as a PakBus router, TCP serial server, TCP serial client, Modbus TCP/IP gateway, and TLS proxy server for HTTPS and user-defined-port communications.

The NL201 also provides a unique mode that bridges the Ethernet and CS I/O ports. This allows access to the internal IP functionality of the CR800, CR850, CR1000, and CR3000 (e.g., web page access, email, FTP). Adding a NL201 configured in this manner to a CR800 is analogous to adding a NL120 to a CR1000’s peripheral port.


Power Connector CS I/O port or DC barrel connector (not powered over USB)
Power Requirements 7 to 20 Vdc
CS I/O Port SDC 7, 8,10, or 11 (does not support ME)
RS-232 Port DTE
USB Port Micro-B
  • Device Configuration Utility over USB or Ethernet
  • Terminal menu over Telnet
  • Terminal menu over RS-232
Temperature Range
  • -25° to +50°C (standard)
  • -55° to +85°C (extended)
Connections/Routes Supported
  • Supports 50 simultaneous TCP connections.
  • Up to 10 of the 50 TCP connections can be used for TLS.
  • PakBus Router supports 50 routes.
  • 15 Modbus Server Transactions (maximum)
Dimensions 16 x 6.73 x 2.54 cm (6.3 x 2.65 x 1 in.)
Weight 177 g (6.3 oz)

Current Drain

Active 50 mA (@ 13 Vdc)
Forced Standby 2 mA (available when using Ethernet-to-CS I/O Bridge Mode)

Communication Rate

RS-232 Port 1200 to 115.2k bps
CS I/O Port 9600 to 460.8k bps
Ethernet 10/100 Mbps


RoHS Compliant
European Standards Meets requirements for a class B device under European Standards.
Application of Council Directive(s) 2004/108/EC
Standards to Which Conformity Is Declared EN61326-1;2013


Datalogger Considerations

Datalogger Serial Server PakBus Router Bridge Mode
CR200(X) Series
CR9000X *



♣The CR300 connects to the NL201 using a 10873 serial that is not supplied with the CR300 or the NL201. The CR300-series dataloggers are not compatible with the bridge mode functionality in the NL201 interface.
* Although compatible, the CR9000X does not need an Ethernet interface because it has an on-board Ethernet port.
** It is possible to use an NL201 to connect to a mixed-array datalogger (e.g., CR10, CR10X, CR23X, 21X, CR7) by using an SC32B between the datalogger's CS I/O port and the NL201's RS-232 port.


NL200 / NL201 Drivers () 01-01-2014

Windows USB drivers for the NL200 Series are installed via the Device Configuration Utililty. In the Device Configuration Utility, click on the link "install the device driver" in the main body of text for the NL200 Series.

Note: Drivers must be installed before connecting the NL200 / NL201 to your computer.


NL200 / NL201 Firmware v.8.01 (571 KB) 12-05-2016

Current NL200 / NL201 firmware. Requires the Device Configuration Utility and a USB micro cable.

Note: When updating to OS 8.01 from OS 6 or previous, settings will be reinitialized to factory defaults. When updating to OS 8.01 from OS 7, settings will be retained.

View Update History

Frequently Asked Questions

Number of FAQs related to NL201: 13

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  1. After the OS has been sent, the NL201 will automatically be reset. There is no need to do it manually.

  2. No. A connection to the NL201 must be made to configure it for bridge mode. 

  3. Yes. An OS can be uploaded remotely over TCP/IP using our Device Configuration Utility (DevConfig) software. This method will not work, however, if the device has been configured to operate in bridge mode or if the device has not been configured with a valid IP address.

    To upload the OS over TCP/IP, do the following:

    1. Open DevConfig.
    2. Select NL200 from the list of device types.
    3. Click the Send OS tab.
    4. Follow the instructions listed in the “Download via Ethernet” section.
  4. The NL200-series of devices can be set to bridge the Ethernet or Wi-Fi interface and the CS I/O interface. All packets that come into the device via Ethernet or Wi-Fi will be transferred to the datalogger over the CS I/O port. This enables the datalogger to make all of its IP-related services available. Configuring an NL200-series device with bridge mode enabled is analogous to adding a native Ethernet or Wi-Fi port to the datalogger. Bridge mode does not use PPP.

  5. The NL201 and NL240 are available options.

  6. The NL121 plugs into the datalogger and doesn't require an additional cable to work. The NL121 also doesn't take up much extra space. Because the NL121 has a faster interface to the datalogger than the NL201 does, the NL121 communicates faster.

    The NL201 has to be mounted next to the datalogger and requires a cable to connect to it. Also, the NL201 requires some additional configuration so that it will work with the datalogger. For example, choices have to be made regarding how the NL201 is connected to the datalogger. 

  7. The NL201 and NL240 are powered via the DC barrel connector and/or the CS I/O port. Sometimes, users who are using the network link
    interface as a serial terminal server, PakBus router, or Modbus gateway want to connect their devices via the CS I/O port while
    providing power only through the DC barrel connector and a 12 V source (such as a datalogger SW12V output). In this scenario, a jumper
    inside the NL201 or NL240 can be removed, preventing the interfaces from always being powered by the CS I/O connections. For more
    information, refer to the instruction manual for the interface.

  8. Yes. For example, the NL115 allows the CR1000 to communicate over a local network or a dedicated Internet connection via TCP/IP. 

  9. Yes. We currently have, and continue to develop, a variety of products that are compatible with IPv6 networking. For example, the NL200/201 and NL240 can serve as IPv6 serial servers for our dataloggers and communications peripherals. We anticipate IPv6 compatibility to be included in the CR800, CR850, CR1000, and CR3000 by mid-2014. 

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