'Lawson Labs, Inc.
'
'April 1987
'
'Sample driver for controlling a DO16 relay board from an LPT1 or LPT2 port
'
CLS : KEY OFF
LPTADDR = &H3BC: ' For LPT2 use LPTADDR= &H378

State% = 0: FOR relay% = 1 TO 16: GOSUB Changerelay: NEXT  'initialize to off
lastrly% = -1  'keeps track of last relay turned on. Init to an invalid number

Enterit:
INPUT "Enter relay number (1-16) "; relay%
IF (relay% > 16) OR (relay% < 1) OR (lastrly% = relay%) THEN GOTO Enterit
IF (lastrly% <> -1) THEN
  State% = 0: rly% = lastrly%
  GOSUB Changerelay           ' turn off the last one
END IF
State% = 1: rly% = relay%
GOSUB Changerelay             ' turn on this one
PRINT rly%; " selected"
GOTO Enterit

Changerelay:
 'Set relay # RLY% to STATE%
CODE% = State% * 32 + (rly% - 1) XOR 207
OUT LPTADDR, CODE%
 ' wait 2 ms or more
OUT LPTADDR, CODE% - 64
 ' wait 2 ms  or more
OUT LPTADDR, CODE%
 ' wait 2 ms  or more
IF State% = 1 THEN lastrly% = rly%
RETURN

'
'DO16 relay contacts: Max voltage= 140 volts
'                      Max current= 0.5 amps
'                      Max power=   8 watts (volts * amps)
'
' Interconnections:
' LPT1 or LPT2 connector pin#       DO16 terminal         MODEL 66 terminal
'              2 ------------------ A   (address)---------same
'              3 ------------------ B   (address)---------same
'              4 ------------------ C   (address)---------same
'              5 ------------------ D   (address)---------same
'              6 -----------------------------------------E   (address)
'              7 ------------------ F   (on or off)-------F   (address)
'              8 ------------------ G   (strobe)
'             14 -----------------------------------------OUT  output
'             25  ------------*-----G   (ground)--------- GND  (ground)
'                             |     +5  (+5 VDC)--------- +    (+5 VDC)
'                             |     |
'                             |     |
'                             |     |
'  5 Volt DC Power Supply:  GND    +5
'