Hardware manual

5901 High Speed Dialup Modem Hardware Manual
October 19, 2007
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Example: +IPR: (0,300,1200,2400,4800,9600,19200,38400,57600,115200)
10.4.22 +ITF=a,b,c - Transmit Flow Control Thresholds
The +ITF command determines the flow control thresholds used by the modem for transmit data
from the DTE.
This optional compound parameter allows the DTE to determine the input buffer size in the modem
for data on circuit 103 (transmit data) from the DTE, to control the thresholds used for flow control
of such data, and to control how often the modem reports to the DTE the number of octets in this
buffer. The DTE can adjust its own thresholds for flow control of data on circuit 104 (received data)
from the modem.
Command: +ITF=[a[,b[,c]]]
a Determines the threshold, in octets, above which the modem will generate a flow off signal.
Applicable in Synchronous Access and Frame Tunneling modes. Default <off> value is 255.
For the a and b subparameters, the input buffer is assumed to reside between the modem’s
V.24 interface and the Synchronous Access protocol layer; i.e., the buffer count includes all
octets, including EM codes, received from the DTE, with the exception of DC1 and DC3 if
these are used to signal <modem-by-DTE> flow control.
The modem returns the ERROR result code if the DTE specifies that the <off>
subparameter be set to a value less than or equal to the <on> subparameter; in this case, the
current parameter value settings are not modified.
b Determines the threshold, in octets, below which the modem will generate a flow on signal.
Applicable in Synchronous Access and Frame Tunneling modes. Default <on> value is 64.
c Not supported. A fixed value of zero is used and reported.
Reporting Selected Options:
The modem sends a string of information text to the DTE consisting of selected options in response
to the following command:
Command: +ITF?
Response: +ITF: a,b,c
Example: +ITF: 255,64,0 Default values
Reporting Supported Options:
The modem sends a string of information text to the DTE consisting of supported options in
response to the following command:
Command: +ITF=?
Response: +ITF: (list of supported a values),(list of supported b values),(list of supported c
values)
Example: +ITF: (0-255),( 0-255),(0)
The maximum reported “a” value is the input transmit data buffer level at which the modem signals
a transmit data overrun indication to the DTE.