CHAPTER 1 - INTRODUCTION
1.1 FUNCTIONAL DESCRIPTION
The MSD-4C is an asynchronous code-operated switch that has five RS-232 serial
ports consisting of a Master Port and four sub-channel ports. The user will enter an
ascii command from a computer that is transmitted over the Master port to the units
internal circuitry. The ASCII command automatically switches the
Master Port data path
to one of the four sub-channel ports as specified in the ASCII command. The data path
is secure and does not allow the other data ports to access the Master Port until an
ASCII command is reissued.
Code-operated switches are useful in environments where remote switching is needed
for file-sharing or monitoring purposes. For example, you could use an RS-232 serial
code-operated switch to remotely switch between pieces of data terminal equipment
(DTE), such as servers or routers for running diagnostics from a remote console.
The MSD-4C operates in two primary modes of operation known as Text or Graphics.
1) In
Text Mode
, the unit will enter switch-time whenever it receives an arming
character. It will select the sub-channel that is specified by the channel select character.
The remaining text will pass through the unit until another arming character is
encountered.
2) The
Graphics Mode
is capable of passing graphics data while still maintaining code
control. In this mode, an arming character will only be recognized as an arming
character if it is preceded by a pause in data transmission of a minimum length of time.
The MSD-4C has status LED’s for the Master Ports control and data signals.
Additionally the unit has LED’s showing the sub-channel port connected. Internal
circuitry allows the user to select a time out of a data port. The time-out will allow other
data ports to then be accessed.
MSD-4C INSTALLATION AND OPERATIONS MANUAL
Page 1
TYPICAL APPLICATION
Figure 1.1