User`s manual

U.S. Robotics I-modem Command Reference
Flow Control • Page 10-6
&I4 Hewlett PackardÐTerminal mode. Applies only to I-modems attached to
terminals in an HP system that uses the ENQ/ACK protocol
. Use in ARQ
mode only.
&I5 Enable ßow control when the connection is not under error control. For this
to work, the remote device must also have &I5 capability.
In ARQ mode, an I-modem set to &I5 operates the same as it does when set
to &I2. It acts on your XON/XOFF commands, but does not pass them to
the remote system. The error-control protocol
enables the devices to con-
trol the ßow of data on the phone link.
In non-ARQ mode, an I-modem set to &I5 operates as though ßow control
were disabled (&I0); it does not look for your typed XON/XOFF com-
mands. However, it does look for XON/XOFF characters coming in over
the phone link. When the remote device sends XON/XOFF com-mands, the
I-modem either resumes or stops transmitting data over the link and drops
the characters from the data stream.
If both devices are set to &I5, operators at each end can signal the remote
device to stop sending, thereby controlling the data ßow on the phone link