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Description:
The &C command controls the behavior of the DCD (Data Carrier Detect) signal (pin
8 on the RS232E/V.24 interface). Normally, DCD goes high when the ProxyServer
establishes a connection, and drops when the connection is lost. However, you can
also force DCD to remain high at all times, or to remain high except for a brief drop
following a disconnect.
&C0
&C1
&C2
Command:
&Dn
Function:
DTR Control
Values:
n = 0, 1, 2, or 3
Default:
&D1 (Exits Data Mode and re-enters AT command mode)
Description:
The &D command controls how the ProxyServer responds to the DTR (Data
Terminal Ready) signal on pin 20 of the RS232E/V.24 interface. A high DTR signal
tells the ProxyServer that the connected computer is ready to communicate.
&D0
&D1
&D2
&D3
Note: If the user wishes to accept calls while DTR is low, the ProxyServer must be
configured to ignore DTR. This is accomplished by entering AT&D0<cr>. With this
configuration, the ProxyServer is able to accept calls while DTR is low. If this
configuration setting is not made, the TA rejects incoming calls until DTR is high
while the calls comes in.
Command:
&En
Function:
Flow Control
Values:
n = 3–7, 12, 13
Default:
&E4, &E7, &E13
Description:
The &E command selects the method by which the ProxyServer controls the flow of
data to and from the computer, to prevent either device from accepting data faster
than it can handle. The ProxyServer provides flow control in both directions. When
the ProxyServer halts data flow, it's called flow control; when the computer halts data
flow, it's called pacing.
&E3
&E4
&E5
&E6
MTPSR1-202ST
DCD is forced high at all times.
DCD goes from low to high when the ProxyServer establishes a connection
(DCD normal).
DCD drops briefly following a disconnect, then goes high again. Register
S10 defines how long the DCD signal remains low after a disconnect.
The ProxyServer ignores the DTR signal.
When DTR goes low, the ProxyServer exits data mode and re-enters AT
command mode.
If DTR goes low when the ProxyServer is online, the ProxyServer hangs up,
returns to command mode, and disables autoanswer. If the ProxyServer is
offline, it neither answers nor dials while DTR is low.
When DTR goes low, the ProxyServer resets the data port and disables
autoanswer. If DTR goes low when the ProxyServer is online, the
ProxyServer hangs up, resets the active configuration to the stored
configuration, and disables autoanswer.
Disable flow control by the ProxyServer.
Hardware flow control. &E4 causes the ProxyServer to use the CTS signal
on pin 5 of the RS232E/V.24 interface to regulate flow control. When CTS
goes low, data flow from the computer is suspended until CTS goes high
again. This method works with pacing, which uses the RTS signal on pin 4.
Hardware flow control cannot be enabled unless an error correction protocol
is selected.
XON/XOFF flow control. This is an in-band method, in which the XON and
XOFF characters (^Q and ^S respectively) are inserted into the data stream,
rather than using separate control lines. When an XOFF character is detected,
the data stream is suspended until an XON character is detected. The
drawback to this method is that some files may contain these characters,
causing the file transfer to be suspended indefinitely.
When XON/XOFF pacing is active, the ProxyServer responds to and
discards the XON/XOFF characters from the computer.
Appendixes
109
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