Documentation for PC-RELAY Kit 74, DOS based utilities   October 1995.


There are three DOS-based utilities that accompany the PC-RELAY kit:

1.	RELAY	used to output a hex byte to the designated parallel port
2.	DELAY	used to wait for a user defined number of seconds
3.	WAITFOR	used to wait until a specified time (HH:MM)

Batch files using these programs can be written to control the operation
of any of the eight relays on the PC-RELAY board.

The programs were written using Borland Turbo C/C++ 3.0. The original C
source code is also provided.



RELAY.EXE

Syntax: RELAY <hex byte>	or
	RELAY/1 <hex byte>	or
	RELAY/2 <hex byte>

Output the <hex byte> to the specified parallel port. The value of <hex
byte> can be in the range 00h to FFh.

The parallel port can be specified following the command name (see command
syntax). If none is given then LPT1 is used by default.

Example:	RELAY 5A

Outputs the hex value 5A (binary 0101 1010) to LPT1, causing relays RL7,
RL5, RL4 and RL2 to operate.



DELAY.EXE

Syntax: DELAY <seconds>

Waits for the number of <seconds> before exiting. The maximum number of
seconds allowed is 32,767. The program does not test for values greater
than 32,767 or less than 0.

During operation, the remaining number of seconds is displayed. The
program can be terminated at any time by pressing the "ESCAPE" key.

Exiting via the "ESCAPE" key causes the program to return an exit code of
"1". This condition can be detected within batch files using the "IF
ERRORLEVEL ..." command.

Example:	DELAY 100

Causes the program to wait until 100 seconds has elapsed before exiting.



WAITFOR.EXE

Syntax:	WAITFOR <hh:mm>

Waits until the specified time <hh:mm> is reached before exiting. A 24
hour clock is used to specify the time. The program does not test for
invalid time settings eg. 25:00 or 12:75, etc.

During operation, the current time in HH:MM:SS is displayed and updated
every second. The program can be terminated prematurely by pressing the
"ESCAPE" key.

Exiting via the "ESCAPE" key causes the program to return an exit code of
"1". This condition can be detected within batch files using the "IF
ERRORLEVEL ..." command.

Example:	WAITFOR 18:30

Causes the program to wait until 6:30pm before exiting.



The following short batch file illustrates the use of the three utilities.
The batch file waits until the time is 11:00am and then sequentially
operates each relay in turn for 5 seconds. Pressing the "ESCAPE" key
during operation causes the batch program to terminate immediately. All
relays are released upon exit.


waitfor 11:00
@if errorlevel 1 goto end
relay 01
delay 5
@if errorlevel 1 goto end
relay 02
delay 5
@if errorlevel 1 goto end
relay 04
delay 5
@if errorlevel 1 goto end
relay 08
delay 5
@if errorlevel 1 goto end
relay 10
delay 5
@if errorlevel 1 goto end
relay 20
delay 5
@if errorlevel 1 goto end
relay 40
delay 5
@if errorlevel 1 goto end
relay 80
delay 5
:end
relay 00


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