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1992-12-22
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63 lines
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Multiplexers & pcANYWHERE
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A little Background on MUXes:
Multiplexers (MUX's) allow multiple connections over a single phone
line. The phone line may be a leased line or dial up line. Each device
is connected to a channel on the MUX. The MUX then combines all of
the signals from each channel into a single composite signal. This
signal is then sent through a modem over the phone line. A matching
MUX on the receiving end then "de-multiplexes" the signals and distributes
to each appropriate channel. The below diagram illustrates a MUX usage
scenario with three channels active 1, 2, and 3:
Leased
REMOTE1===\ or /===HOST1
HOST2====>===(MUX)===(MODEM)~~~~~~~\/\_______(MODEM)===(MUX)===<====REMOTE2
REMOTE3===/ Dial-up Line \===HOST3
The modems, which may be internal to the MUX, operate in synchronous mode.
Each channel behaves as if it were directly connected to the other device
at the matched MUX as shown above (ie. REMOTE1 to HOST1, 2 to 2, and 3 to 3)
Customer's MUX configuration must be operational in order to use pcANYWHERE.
Specifically, data must be flowing through the channel(s) to be used by
pcANYWHERE. (To test this, the Remote to Remote test can be used to determine
if data can flow across the channel correctly).
pcANYWHERE's Hardware Configuration:
______________________________________________________________________________
REMOTE HOST
====== ====
Modem: None None
*Date rate: (set to speed of MUX) (set to speed of MUX)
*Parity: None None
*Flow control: RTS/CTS RTS/CTS
Conn. started by: Carrier Detect (DCD) Receive 2 <CR>'s
Conn. ended by: Carrier Detect (DCD) Carrier Detect (DCD)
* These options depend on the Multiplexer used.
______________________________________________________________________________
Note: Multitech's MM904 Statistical Multiplexers:
1. These MUX's were tested with multiple pcANYWHERE IV connections
simultaneously.
2. These MUX's operate DTR pacing for flow control. That is, the
MUX looks for DTR to go low when the device cannot accept data and the
MUX's set CTS low when they cannot accept data. Multitech's Tech Support
has suggested wiring RTS signals from the device (PC running pcANYWHERE)
to the DTR signal on the MUX to accomplish hardware flow control.
3. Carrier is always high for any device connected to these MUX's
4. Baud rate in pcANYWHERE's configuration must be set to the baud
rate of the channel used. These MUX's do not "auto baud" their channels.
_______________________________________________________________________________
SYMANTEC has a number of useful documents that are available through this BBS.