Moxa Tech Note

NPort’s Ethernet Modem Mode

NPort’s Ethernet Modem Mode
Tom Lu, Senior Engineer, Moxa Technical Support Dept.
tom.lu@moxa.com

This Tech Note applies to the following NPort models:• NPort DE-211• NPort DE-311• NPort DE-311M• NPort 5100 series• NPort IA5150• NPort IA5250• NPort W2150 Plus
• NPort W2250 Plus
• NPort 6150
• NPort 6250
• NPort 6450
• NPort 6650
What is Ethernet Modem mode?
Ethernet Modem mode is designed to provide true modem emulation, in which theNPort emulates a regular serial modem that accepts AT commands for dial-in/outservice. When configured for Ethernet Modem mode, the NPorts will transmit raw
data back and forth transparently.

PC running DOS
legacy program

RS-232

TCP/IP

RS-232

NPort 1

NPort 2

Serial Device

How to configure Ethernet Modem mode
Before starting the configuration process, press and hold the RESET button for 10
seconds to reset the NPort to factory default values.

Copyright © 2008 Moxa Inc.

Released on March 31, 2008

About Moxa
Moxa manufactures one of the world’s leading brands of device networking solutions. Products include serialboards, USB-to-serial hubs, media converters, device servers, embedded computers, Ethernet I/O solutions,terminal servers, Modbus gateways, industrial switches, and Ethernet-to-fiber converters. Our products are key
components of many networking applications, including industrial automation, manufacturing, POS, and medical
treatment facilities.

How to Contact Moxa
Tel:1-714-528-6777
Fax: 1-714-528-6778

Web: www.moxa.com
Email: info@moxa.com

This document was produced by the Moxa Technical Writing Center (TWC). Please send your comments orsuggestions about this or other Moxa documents to twc@moxa.com.

Moxa Tech Note

NPort’s Ethernet Modem Mode

NPort DE-211/DE-311/DE-311M:
1. Power onthe NPort and then wait until the Ready LED lights up in green.
2. For RS-232 data transmission, set the DE-311’s DIP switches toOFF-OFF-OFF, and set the DE-211’s DIP switches to OFF-OFF-OFF-OFF.
3. Connect the host PC and NPort to the network.
4. Adjust the IP/netmask combination of the host PC and NPort so that they areon the same subnet. The default values for the NPort are
192.168.127.254/255.255.255.0. PING from the host PC to the NPort to verify
that the connection is active.
5. Issue the command # telnet <NPort’s IP> to log in to the NPort’s Telnet
console.
6. Under [OP_mode] choose [Ethernet Modem] for the Application. Under“More settings” configure [TCP port] and [Destination IP addr] so that thetwo NPorts can connect to each other.
7. Open [Serialport] to define the serial parameters for your program and theNPort to match the attached serial device (e.g. 115200, N, 8, 1).
8. Select [Restart] to activate all settings.
NPort 5100/5400/5600 series, NPort IA5150/IA5250:
1. Power on the NPort and then wait until the Ready LED lights up in green.
2. Connect the host PC and NPort to the network.
3. Adjust the IP/netmask combination of the host PC and NPort so that they areon the same subnet. The default values for the NPort are
192.168.127.254/255.255.255.0. PING from the host PC to the NPort to verify
that the connection is active.
4. Issue the command # telnet <NPort’s IP> to log in to the NPort’s Telnet
console.
5. Open Main menu Æ Operating settings Æ Port Æ Operating mode andthen select [Ethernet Modem Mode]. Next, define the [Local TCP port] forlistening.
6. Open Main menu Æ Serial settings Æ Port to define the serial parameters
for your program and NPort to match the attached serial device (e.g., 115200,N, 8, 1).
7. Select [Save/Restart] to activate all settings.
NPort 6150/6250/6450/6650, NPort W2150/W2250 Plus:
1. Power on the NPort and then wait until the Ready LED lights up in green.
2. Connect the host PC and NPort to the network.
3. Adjust the IP/netmask combination of the host PC and NPort so that they areon the same subnet. The default values for the NPort are

Copyright © 2008 Moxa Inc.

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Moxa Tech Note

NPort’s Ethernet Modem Mode

192.168.127.254/255.255.255.0. PING from the host PC to the NPort to verify
that the connection is active.
4. Issue the command # telnet <NPort’s IP> to log in to the NPort’s Telnet
console.
5. Open [Port] Æ [Modes] and set Application to [Ethernet Modem]. Next,
define [TCP port] for listening.
6. Open [Port] Æ [Line] to define the serial parameters for your program andNPort to match the attached serial device (e.g., 115200, N, 8, 1).
7. Select [Restart] to activate all settings.
Note 1: For the NPort wireless Plus series, the Ethernet and WLAN connections
cannot be used simultaneously. If the Ethernet port is connected, the WLAN will
not work. Consequently, if you would like to use the WLAN, be sure to unplug theEthernet first.
Note 2:
1. The default value of [TCP port] is 4001.
2. For the NPort DE-211/311/311M device servers, only those NPorts whose IP
addresses are configured in the [Destination IP addr] column will beallowed to connect to this NPort. Leave this column empty to allow all other
NPorts to connect to this NPort.
3. The NPort’s default IP address for connecting to a wireless LAN is
192.168.126.254.
4. If the DCD signal is required for carrier detection, you will need to wire a
special cable to connect the NPort's serial port to your device or PC as shown
below:
DTE/ Device
NPort
Tx------------------Rx
Rx ------------------Tx
CTS ------------------RTS
RTS ------------------CTSDTR ---------|DCD
DSR ---------|--------DSR
DCD ------------------DTR
GND ------------------GNDCopyright © 2008 Moxa Inc.

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Moxa Tech Note

NPort’s Ethernet Modem Mode

How to test Ethernet Modem mode
Ethernet

RS-232PC s COM port

RS-232

NPort 2

NPort 1

PC s COM port

[Dial-in] at NPort #2
The NPort listens for a TCP/IP connection request from the remote Ethernet
modem or host. The NPort’s response depends on the ATS0 value, as explained
below:

ATS0=0 The NPort will temporarily accept the TCP connection and then send a “RING”(default) signal out through the serial port. The serial controller must reply with “ATA”

within 2.5 seconds to accept the connection request, after which the NPortenters data mode. If no “ATA” command is received, the NPort will disconnect
after sending three “RING” signals.
ATS0>=1 The NPort will accept the TCP connection immediately and then send the“CONNECT <baud>” command to the serial port, in which <baud> represents
the baud rate of the NPort’s serial port. The NPort will then immediately enter
data mode.
Example 1:
You can send AT Commands to NPort #2 via HyperTerminal as shown below:
AT CommandAT
ATS0=1

NPort ResponseOKOK

Description
Test
Ring to auto-answer[Dial-out] at NPort #1
The NPort accepts the AT command ATD <IP>:<TCP port> from the serial port
and then requests a TCP connection from the remote NPort configured for
Ethernet Modem mode. <IP> represents the IP address of the remote Ethernet
modem or PC, and <TCP port> is the TCP port number of the remote Ethernet
modem or PC. Once the remote device accepts this TCP connection, the NPort will
send the “CONNECT <baud>” signal via the serial port and then enter data mode.
Example 2:
You can send AT Commands to NPort #1 via HyperTerminal as shown below:
AT command
ATNPort response
OKATDT 192.168.127.254:4001

CONNECT 115200

Description
Test
Dial up the IP address& Port No.

[Disconnection request]

Copyright © 2008 Moxa Inc.

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Moxa Tech Note

NPort’s Ethernet Modem Mode

When the NPort is in data mode, users can send "+++" from the local serial port
to the NPort to put the NPort into command mode. Enter the command ATH toshut down the TCP connection. Instead, you may also drive the DTR signal to
OFF to shut down the TCP connection. The NPort will return NO CARRIER
through its serial port after 1 second.
Example 3:
You can send AT Commands to NPort #1 or NPort #2 via HyperTerminal as shown
below:
AT command+++
ATH

Copyright © 2008 Moxa Inc.

NPort response
OKOK; NO CARRIER

Description
Enter command mode
ATH0=On-hook (default)

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