Flow Control; Diagnostics; Downline Parameter Loading - Multitech MMH900 User Manual

1.5.3

Flow Control

Flow control regulates the volume of data entering the buffers. When a
particular channel buffer is almost full, a flow control command is issued
which stops further activity until the buffer is emptied. The most common
flow control methods currently used are Xon/Xoff, RS232C signal control
(using DTR or CTS) and ENQ/ACK. The MultiMux supports all three.
MUX INITIATED
FLOW CONTROL
DATA
Channel
Device
Flow control stops the
input of data to the mux
1.5.4

Diagnostics

Diagnostics in a multiplexer network are of considerable importance.
When a multiplexer fails there is not just one operator down, but many.
That is why the MultiMux is equipped with several diagnostic modes that
will test every aspect of the network. The diagnostics include easy-to-
execute tests for each channel, the composite link and for various
components of the MultiMux unit itself. There are nine different test
modes to ensure error free operation. They include Analog Loop, Digital
Loop, Remote Analog Loop, Switch and LED tests, Non-Volatile Memory
test, three other tests and a "Watchdog Timer" reset test.
1.5.5

Downline Parameter Loading

Operational parameters for both local and remote MultiMux units can be
set from one location. The MMH900 series can downline load
parameters to each other, but they cannot send parameters to the
MM16xx/MM32xx and MMH16/MMH32 units. When power is first applied
(or a Reset command is executed) to the local or remote MultiMux,
operational parameters are automatically sent over the composite link to
the remote MultiMux. For this function to work, the 8-position DIP switch
SW1 on the local (sending) MultiMux must be set to the OPEN position
and on the remote (receiving) MultiMux the 8-position DIP switch SW1
must be set to the CLOSED position.
Chapter 1 - Introduction & Description
CHANNEL DEVICE
INITIATED PACING
Mux
Mux
Pacing stops the output
of data from the mux
DATA
Channel
Device
17