Bridging The Gap Between Serial And Network Communication - GE Multinet 4 Instruction Manual

CHAPTER 7: TERMINAL SERVER APPLICATION NOTES
7.2

Bridging the Gap between Serial and Network Communication

MULTINET4 MULTI-PORT SERIAL SERVER & MANAGED SWITCH – INSTRUCTION MANUAL
A Terminal Server is a device or software application that can pass data between a
standard serial protocol link and an Ethernet-based network. The figure below illustrates
passing characters from an RS-232 port over a TCP/IP connection.
Without a terminal server, the host system in the above figure must connect to the DCE
device over a serial cable. Some of the advantages of using a terminal server are:
1. The distance between the computer system and the end device is increased
significantly. The effective maximum range of an RS-232 link is about 10
meters. With a terminal server, the computer system connects to the device
over a network and the effective maximum range is limited only by the latency
requirements of the communicating end systems.
2. Multiple computer systems can communicate with a single RS-232 device.
This would be impossible using just an RS-232 link because it only operates in
point-to-point topologies. The terminal server performs a multiplexing
function that passes data from multiple endpoints over the single RS-232 link.
3. Connections between relatively large numbers of communicating end
systems are supported over a common cabling infrastructure. Without a
terminal server, limitations imposed by the RS-232/485 standards would likely
require many dedicated lines between end systems.
TERMINAL SERVER APPLICATION NOTES
FIGURE 7–1: Serial Over TCP/IP
7–3