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PortBox PL: Serial to Ethernet device server


Warning: This product is replaced by new version PortBox2


Czech version

English version

RS-232/485 serial line - Ethernet converter on TCP/IP and UDP/IP protocol. Built-in virtual serial port support, the remote port can be mapped as for example COM7 in Windows using the HW VSP utility. 9-bit support extension, wide support of RS-485 question-answer communication support.

A typical application is access a remote technology controlled over RS-232 of RS-485, or serial port prolonging via the Ethernet network.

PortBox PL
Big product picture

Basic features

  • 1 RS-232 or RS-485 serial port accessible over Ethernet (TCP/IP or UDP/IP)
  • Virtual serial port driver for windows - for example COM 7 in your PC
  • The device can work in TCP Client or TCP Client/Server mode
  • 9. bit communication support (over RFC2217 or synchronous "Variable Parity" command)
  • Two devices can be connected to each other to create "RS-232 over Ethernet" connection.
  • Wide RS-485 question-answer protocol support in the UDP/IP mode
  • Serial interface parameters: 300..115.200 Bd, 7/8/9 bit communication
  • Free software utility for easy device setup and testing Hercules.
  • A DIN molding or wall mounting version available.
    A "telecommunication" version available (power supply: -48V DC).
  • Data security - predefined IP address range or 128bit TEA encryption
  • Programming libraries for MS Visual Basic, Delphi, Borland C++, JAVA, PHP and other..

Typpical applications

A typical PortBox application is a remote access to a RS-232 / RS-485 technology. You can access the device using the original software, if you use the HW VSP utility. If you want to write your own software, you can use our collection of software examples.

Application examples

  • Connecting serial printer to Ethernet
  • PBX systems  
  • Card readers, RFID
  • Remote RS-232 technology controlling
  • Exchange displays
  • Electronic key systems
  • Sales machines
  • Display systems
  • Security alarms
  • Attendance systems
  • UPS control and logging
  • Data recording
  • CNC machines
  • Chemical and gas chromatographic tools
  • Bar code readers


Download & Datasheets

Flyer Datasheet


Why to use thePortBox device?

  • We can help you solve your problems - as a manufacturer, we are ready to provide you with the best possible technical support.

  • PortBox uses open standards, and we can aswer any question regarding the device..
  • FREE FW UPGRADES - If you own an older device version, contact us and we will provide you with a FW upgrade.
  • Customer applications can be implemented in the device, just contact us and tell us what you need. 


System topology

See picture for typical device connection and basic network protocols.
  • TCP/IP Server   [Client -> Server]
    Portbox waits as a TCP server until any side (PC or server) opens a TCP connection. When the connection is established, the internal buffered data is sent and then the device allows communication as a standard "terminal server".
  • TCP/IP Client/Server    [Server <- Client]
    The PortBox received serial port data into its internal buffer and tries to send them to the server. It will try to open a connection to the preset IP address and port. If the attempt was unsuccessful, it waits for a second in the TCP Server mode and then tries to open the connection again.
  • UDP/IP
    The data is transferred in UDP packets, with no delivery notification.
    The porbox uses a sophisticated "Paketizer", which allows various condition of what can and what cannot be send from the serial line to Ethernet.
  • VSP (The Virtual Serial Port)
    You have a HW VSP software which creates a virtual COM port under Windows OS, so that the device acts like it's connected directly to your PC, though it's a virtual remote port. If the buffer is enabled and the TCP connection is not available, the data is stored into the internal buffer memory. For the full function it's advantageous to enable NVT (Network Virtual Terminal), so the port is RFC2217 compatible.


Technical parameters

Serial port RS-232
+ Data bits 7 or 8 or 9
+ Stop bits, Parity 1 or 2, None / Odd / Even / Mark / Space parity
+ Baud rates 50..115.2 kBd – entire range, step = 50 Bd
+ Data flow control Xon/Xoff, CTS/RTS, None
+ 9. bit (parity) SW control NVT control (RFC2217) + FE prefix synchronous extension
+ Interface 1x DB9M (RxD,TxD,RTS,CTS,GND)
+ Virtual Serial Port SW HW VSP available for OS: Windows 98, 2000, XP, NT 4.0
RS-232 serial port interface
+ RS-232 Buffer memory 2 048 B for incomming data  (33 792 B for Revision 2)
+ Buffer overflow signalling Network: None
RS-232: HW or SW handshake if internal buffer is full
+ RS-232 DTR signal DTR output – defined voltage level, +12 / 100 mA available
+ Used RS-232 signals RxD,TxD,RTS,CTS, (DTR output – defined voltage level only)
RS-485 serial port interface
+ Termination Rev. 1: internal termination, DIP3,DIP4 control
Rev. 2: None, for longer lines external termination required
+ Isolation RS-485 line not galvanic isolated to the device’s power supply
+ RS-485 serial port settings Half duplex and no HW echo recommended
Ethernet port
+ Interface RJ45 (10BASE-T) – 10 Mbit or 10/100 Mbit network compatible only!
+ Compatibility Ethernet: Version 2.0/IEEE 802.3
+ Supported protocols IP: ARP, UDP, TCP + NVT (Network Virtual Terminal)
+ Supported TCP/IP modes TCP Server, TCP Client/Server
+ TCP connection close timeout timeout 50s (with enabled NVT – can be prolonged by ACK/NOP)


+ Operating temperature +5 .. 50 °C
+ Storage temperature -10 to 85 °C
+ Humidity (non-condensing) 5 to 95 %


Physical parameters
+ Power supply requirements 8-15V / Max. current consumption 200 mA DC
  - barrel (coaxial) power connector, GND on the shield
Functional parameters
Device SETUP configuration options - RS-232 Setup over any RS-232 terminal with DIP1=ON
- TCP/IP Setup - using any telnet terminal on the TCP/IP 99 port
- Hercules SETUP utility via UDP (basic network parameters only)
Diagnostic LEDs - Power (green)
- Link & Activity (yellow)

Remote parity control - 9. bit communication

The "Variable Parity" mode is primarily designed for controlling the 9th parity bit for 9-bit communication.

There are two ways of controlling the parity:

  • The remote serial port configuration change over NVT
    This way is not very useful, because it does not sychronize the parameter change with the serial port data.
  • The parity change for the following character using "Variable Parity"
    This will modify the parity for one following character.

If the VIRTUAL PARITY (&V: Variable Parity On) mode is allowed, you will change the parity for the following character if you insert a 2 byte sequence 0xFE 0x50 before the character.

Pay attention to the 0xFF and 0xFE characters

Beacause of the "NVT" and "Variable Parity" modes support, you need to respect 0xFF and 0xFE characters in the data flow as a prefix for NVT (0xFF) and Variable Parity (0xFE) control. This means, that if you want to send the "0xFF" character to the serial port, you need to send it doubled over TCP/IP.

Example: you are sending "0xFF 0xFF 0x41 0xFE 0xFE" over TCP/IP, but the Charon module will send only 3 characters: "0xFF 0x41 0xFE". If you do not double the FF and FE, they will be processed as a commands!

>> AN23: Serial Tx Pause for Eth/RS-232 converter

Questions and suggestions


If you are interested in any of these modifications, need help implementing them in your projects, or if you want a specific customer solution, feel free to contact us..


Embedded PortBox version - Charon I module

The box version can be replaced with a module, that can be fitted in you PCB as any integrated circuit.
The Charon 1 module is about 34x42 mm with 24 pins (2x12 pins with 100 milů diameter). You only need to place a supplied transformer and RJ45 connector outside the module.  

The Charon I module is ideal solution that can be integrated in your application, if you already worked with the PortBox Device.

for details, see Charon I description



Useful SW

  • Hercules SETUP Utility
    This utility will help you testing a setting up the device. .
    • RS-232 terminal
    • TCP/IP Client terminal
    • TCP/IP Server terminal
    • UDP terminal
    • UDP Config
    • Test mode (TCP/IP NVT commands + TEA)

    This utility is completely free to use and distribute..  
    Hercules Setup Utility            

  • HW Virtual Serial Port
    Virtual serial port driver for windows is a software tool for adding a virtual COM port to your windows system. All the data from this port is then redirected to another HW interface.
    • Unlimited, free Virtual Serial Port for any TCP/IP device.
    • Designed for Windows 2000, XP.
    • If the device supports RFC 2217 (NVT), you can setup all the serial port parameters (speed, parity, stop bits).
    • OThe driver works as a "TCP client", but it can be also used in "TCP server" mode.
    • Logging all the communication into a file, to make debugging easier.
    • You can create more virtual serial ports on one system using command line parameters.
    • The software can be run o a windows startup and hidden to the system tray.

    HW Virtual Serial Port            

FAQ & Support

Ask for the price or details:
 - Web:  http://
Country: *

Spam protection. How many is SIX times six?

Q: How to set the device's IP address?
A: The IP address can be set in the RS-232 setup mode (PortBox is connected using the supplied LapLink cable), or using a windows software - Hercules. You can set the IP address In the UDP Config tab, according to the MAC address of the device found on you network (you can see the MAC address on the label on the bottom of your device). More information can be found in the "(Quick SETUP)" chapter in the datasheet.

Q: I need to connect a device, which uses a remote serial port, is that possible?
A: Yes, PortBox is designed for this kind of application. You can also use your original software, if you need. All you need to do is install our HW VSP utility to use the remote serial port on your PC as any standard COM port.

Q: Does the remote serial port change it's settings according to the port in my PC?
A: Yes, PortBox uses the RFC2217, which changes the serial port parameters according to your settings.

Q: What is the difference between the PortStore2 and PortBox devices?
A: Both devices are designed for RS-232/485 to Ethernet conversion and are almost identical. PortStore2 has additional Flash memory for storing incomming serial port data, when TCP/IP connection is not available. PortBox has got only the 1kB/1kB RAM cache memory.

Q: Can I prolong the RS-232 line over Ethernet with using two PortBox devices?
A: Yes, you can find the detailed configuration in the device datasheet.

Q: Can I use more Virtual serial ports on one PC ?
A: This is generally possible with using the HW VSP command line parameters, refer to the datasheet for detailed description.

Q: Is there a PortBox with more serial ports available?
A: We are working on a produst called "Hyperion", which should be available in the spring 2005, and which has 2 RS-232 ports. When the box is available, we will publish it on our website and the HW Group newsletter, which you can subscribe to.

Q:  How do you ensure communication security?
A:  For increasing the security of data transfer in TCP mode it's possible to authorize both sides on establishing any TCP/IP connection via TEA 128 algorithm with symmetric signature. The configured password of both sides then won't go through the network. This option is possible only for TCP/IP connection. UDP mode is designed only for local networks. Detailed description of TEA can be found in the handbook “Programming of Ethernet Applications” on our website. You can also set the device to communicate with one IP address only. It will not even answer PING command from other addresses.

Q:  Is it possible to prolong the connection timeout?
A:  Standard limit after which the connection is terminated in case of no data flow is 50s. It is possible to enable option „K: Keep connection“, which sends, in 10-second intervals, the NOP command into the open NVT connection.

Q: Can I control the binary inputs and outputs on the RS-232 (DSR, DTR, RI, CD..)?
A: Yes, using the RFC2217 you can control the RTS output and read the CTS input. However, if you need to use more binary inputs/outputs, use the IP Relay, or the I/O Controller.

Q:  Are you planning to publish some software examples for PortStore2?
A:  Yes, check our Support & Download page for many examples for Borland C++ and Delphi (as well as Visual Basic , JAVA and PHP ). We will soon release a software for reading the buffered data.



Available now, you can have it on your table in 3 days! We have a minimum of 20 pcs in stock at all times. It can be shipped via FedEx next day all over the world. We accept payement by Credit Cards (you have to print, fill in and fax the OrderForm) or Wire Transfer, check our prices in the PriceList.
Or try to contact your nearest distributor of our products - International Distributors .

The standard PortBox set shipment includes:

  • A PortBox PL box
  • A power adaptor (you can choose Europe or United Kingdom or USA version)
  • RS-232 connecting ( LapLink ) cable for device setup in terminal mode.
  • Printed Manual, CD with software..

Ordering versions

The PortBox can be supplied in several versions, according to the bellow described ordering number. If you do not specify a device version in your order, we will send you a preffered type. The delivery terms of the non-preffered types should be verified by phone or requested in your order confirmation.

OID Device types
600 294
PortBox PL set (photo)
Recommended starting set, it contains:
 - PortBox PL [600293]
 - EU Power adaptor [600080] (can be replaced by US or UK type)
 - DB9 LapLink cable 2m [600063]
 - Manual, CD
600 293
PortBox PL - just unit plastic box (photo)
PortBox PL device - standalone unit, no power adaptor or cabling..
600 295
Wall mounting profile "C" size (photo)
600 301
Dual Lock fastener (product photo, usage: photo1, photo2)
600 025
DIN Rail box fastener (product photo, usage: photo1, photo2)
600 062 PortBox set - revision 2   (Warning: old type, use another..)
600 061 PortBox revision 2 (photo)   (Warning: old type, use another..)
600 060 PortBox set - revision 1 (photo)   (Warning: old type, use another..)
600 059 PortBox revision 1 (photo)   (Warning: old type, use another..)

Other accessories



Related products

  • PortStore
    2048 kB buffer memory. The stored data can be accessed over Ethernet (TCP/IP). Typical PortStore application is buffering data from PBX, or remote serial device access.
  • IP Relay
    2 Relay contacts + RS-232/485 converter , supports the Server and Client/Server mode, NVT, TEA authorisation, RS-232 "tunneling" over TCP/IP i UDP/IP etc..  
  • HW Virtual Serial Port
    Free Virtual Serial Port driver for Windows is a software tool, which adds a virtual Comm port to the system, for instance COM5, and all the data from this port is re-directed to another TCP/IP device on the Ethernet network.  
  • Eth. I/O Controller
    Connecting binaty inputs/outputs to Ethernet, together with the serial line. In the Server mode, the binary input/outputs can only be monitored, in the TCP Client/Server mode, the box will report input changes.  
  • Charon I module
    Embedded serial line to ethernet converter module, you can connect measuring devices, SNMP interface, thermometers etc...