Dec 312017
 
Control the serial port hardware handshake lines.
File HANDS11.ZIP from The Programmer’s Corner in
Category Communications
Control the serial port hardware handshake lines.
File Name File Size Zip Size Zip Type
HANDS.COM 684 510 deflated
HANDS.DOC 2685 1190 deflated

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Contents of the HANDS.DOC file



HANDS V.1.1 (c) W.C. Parke, 1990

HANDS is a serial port handshake setting program for the IBM PC and
compatibles. Some communications programs do not properly set the
serial port hardware handshaking lines to allow modems or other
communications devices to recognize that the computer is ready to send
data. This can mean that these device will not recognize commands or
data sent to it from the computer. HANDS will let the user set the
Data Terminal Ready and Request to Send lines on or off.

The DTR and RTS lines are wired to pins 4 and 20 on the IBM RS-232 25-
pin serial port connector (pins 7 and 4 on the 9-pin PC AT connector).
Some serial cables have shunt wires which physically hold the DTR and
RTS lines high by connecting them to their mates: The DSR and CTS lines
(pins 6 and 5 on the 25-pin connector; 6 and 8 on the 9-pin connector).
Otherwise, they are used by software to communicate when the computer
or receiving device is busy or inactive.

Syntax: HANDS {on,off}{/n}

where n is a serial port index ( 1 to 4 )

Examples: HANDS ON turns on all serial port DTR and RTS lines
HANDS ON/1 turns on DTR and RTS on COM port 1
HANDS OFF turns off all serial port DTR and RTS lines

Messages:

Without command line parameters, or with an incorrect parameter,

HANDS

will give a help screen and exit.

If a successful setting is made, HANDS will issue a message of the form:

COM1-3 Serial Port Handshake Lines DTR and RTS Set On.
or
COM1 Serial Port Handshake Lines DTR and RTS Set On.

If HANDS finds no COM port, it will say so:

No active COM port.

BAT file use:

If you wish to put HANDS in a BAT file and not have any message show
on the screen, use the syntax shown in this example:

HANDS ON/1 >NUL

Technical Notes:

HANDS uses the port addresses stored in the BIOS area of DOS to find
the appropriate COM port. It will not allow setting of an undefined
COM port.

Since HANDS can be used to drop the DTR and RTS lines, it can be used
to force a carrier drop on some modems attached to the serial port.

HANDS can be used to test the activity of a particular serial port
by connecting a LED port tester (with LED lights on the handshake
lines) to the port, then toggling the handshake lines on and off
with HANDS. The corresponding lights should go on and off.

The identification of pins on the RS-232 connector above assumes a DTE
(Data-Terminal-Equipment) port, as on a computer. For a DCE
(Date-Communications- Equipment) port as on a modem or printer, pins
2-3 (data), 4-5, and 6-20 are reversed in function.



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