B&B Electronics ESP902E User Manual

Manual Documentation Number: ESP901-902-3704 

Chapter 1 

3 

The 

 and 

 enable communication with 

serial devices over a LAN or WAN. Serial devices no longer are 
limited to a physical connection to the PC COM port. They can be 
installed anywhere on the LAN using TCP/IP or UDP/IP 
communications. This allows traditional Windows PC software access 
to serial devices anywhere on the LAN/WAN network.  

 connections allow applications using TCP/IP or UDP/IP 

socket programs to communicate with the asynchronous serial ports on 
the 

. In this type of application the 

 is 

configured as a TCP or UDP server. The socket program running on the 
PC establishes a communication connection with the 

. 

The data is sent directly to and from the serial port on the server. When 
using UDP protocol the server can be configured to broadcast data to 
and receive data from multiple IP addresses.  

 

 allows the user to add a driver, to provide a 

virtual COM port on the computer. The new COM port shows up in the 
Device Manager. Windows programs using standard Windows API 
calls are able to interface to virtual COM ports. When a program on the 
PC opens the new COM port, it communicates with the remote serial 
device connected to one of the ports on the 

.  

After connection, the LAN is transparent to the program and serial 
device. Applications are able to work just as if the serial device is 
connected directly to a physical COM port on the computer. The virtual 
COM port software converts the application’s data into IP packets, 
sends it across the network to the 

, which converts the IP 

packet back to serial data and sends the data out a serial port located on 
the 

. 

To use this mode, the 

 must be set to either TCP/server or 

UDP/server with a designated communication port number. The virtual 
COM driver is the TCP or UDP client.  

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Chapter 1 

Manual Documentation Number: ESP901-902-3704 

 

is also called serial tunneling. In this mode any two serial 

devices that can communicate with a serial link will be able to 
communicate using two 

 and the LAN. 

Two 

 are connected to a network, one configured as a 

TCP or UDP client and the other as a TCP/UDP server. When setting 
up the server the remote IP address section must contain the address of 
the client. This will allow the client’s IP address to pass the IP address-
filtering feature of the server. Conversely, the Remote IP address of the 
client must contain the server’s IP address. Both communication port 
numbers must be the same.  

The 

 protocol connection provides a reliable 

communications connection in 

 or with

 

. This feature restores the connection if 

communications are temporarily lost at either end due to loss of power 
or Ethernet connection. 

Without this feature a device that loses a connection and stops 
communicating would not be able to reconnect without human 
intervention. A TCP data connection can be lost when there is a power 
failure or temporary loss of an Ethernet connection on either the client 
or server. If a loss occurs the Heart Beat feature will try to reconnect 
the TCP data connection every five seconds until communications is 
established again. The Heart Beat feature is available for use in 

 

 and 

 

. This is not available 

when using a UDP application.