Multitech ISIHI-2S User Manual page 100

if DTR goes high, then &D4 will behave like &D1.
Note: If you want to accept calls while DTR is low, the TA must be configured to ignore DTR. This is
accomplished by entering AT&D0<cr>. With this configuration, the TA 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.
&En Flow Control
Values: n = 3–7, 12, 13
Default: &E4, &E6, &E13
Selects method by which the TA controls the flow of data to and from the computer, to prevent
either device from accepting data faster than it can handle. The TA provides flow control in
both directions. When the TA halts data flow, it is called flow control; when the computer halts
data flow, it is called pacing.
&E3 Disable flow control by the TA.
&E4 Hardware flow control. &E4 causes the TA to use the CTS signal 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.
&E5 XON/XOFF flow control. This is an in-band method, where 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.
&E6 When XON/XOFF pacing is active, the TA responds to and discards the XON/
XOFF characters from the computer.
&E7 When XON/XOFF pacing is active, the TA responds to the XON/XOFF
characters and passes them through the communications link to the remote
device, thereby pacing the remote terminal adapter as well.
&E12 Disables pacing
&E13 Enables pacing.
#Xn Send Single/Multiple Xoff Characters
Values: n = 0 or 1
Default: #X0
Allows the TA to send either a single or multiple Xoff characters to exert flow control to the
terminal. The #X0 command (factory default setting) causes one Xoff to be sent until the TA's
buffer reaches the Xon level. The #X1 command causes an Xoff to be sent for every character
received after the TA reaches its buffer full level.
#X0 One Xoff character sent until the buffer reaches the Xon level (default)
#X1 Multiple Xoff characters sent for every character received after buffer reaches
the full level.
Chapter 5 - AT Commands
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