Technical data

Introduction
2 Chapter 1 Manual Documentation Number: ESP904-4513m
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax [phone] – www.bb-elec.com
B&B Electronics Ltd – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph [phone] – Fax [phone] – www.bb-europe.com
ESP904. The LAN becomes transparent to the serial device and the
software running on the PC.
 Heart Beat Connection - selectable protocol ensures reliable
communications in Virtual COM Port or Paired Connection modes. This
feature restores the connections if communications are temporarily lost
at either end due to loss of power or the Ethernet connection.
Communication Modes
The ESP904 enables 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.
Direct IP Mode
Direct IP connections allow applications using TCP/IP or UDP/IP socket
programs to communicate with the asynchronous serial ports on the ESP904.
In this type of application the ESP904 is configured as a TCP or UDP server.
The socket program running on the PC establishes a communication
connection with the ESP904. 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.
Virtual COM Mode
Use Install Virtual COM 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 ESP904.
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 ESP904, which converts the IP packet back to serial data and sends the
data out a serial port located on the ESP904.