Multitech MMH900 User Manual page 143

minicomputer so that the mux's buffer capacity is not exceeded. We
chose Xon/Xoff flow control for this example and are setting pace ON for
all channel devices.
NODE 1 NODE 1
Channel Channel
1 1
2 2
3 3
Mini- Mini-
4 4 Mux Mux
Computer Computer
5 5
6 6
7 7
8 8
MiniComputer Flow Control
In the example below, the flow control on the minicomputer works as
follows:
Channel
1
2
3
Mini-
4
Computer
5
6
7
8
Data
A.
Flow Control
B.
off
Flow Control
C.
on
Data
D.
A. Data volume from the mini for any particular channel is appropriate
for the mux to process and transfer on to the link.
B. Data overwhelms a channel's mux buffer and the mux sends a stop
data Flow Control (OFF) signal to the mini stopping data output.
C. The mux buffer sufficiently enpties to allow additional data transfer,
Appendix F - Flow Control Background
NODE 2
Channel
1
Link Link
2
3
Mux
4
5
6
7
8
Link
Mux
mux process
data to the link
mux buffers
full
mux buffers
empty
mux processes
data to the link
Printer
PC
PC
PC
PC
PC
PC
PC
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