B&K Precision 9171-9174 - Manual - Manual (Page 91)

79
INPUT
Digital input for representing logic high (1) is 5 V, and for logic low (0)
is 0 V.
Minimum voltage for logic high (1) must be at least 3.15 V.
Maximum voltage for logic low (0) must not exceed 1.35 V.
To setup any of the 8 pins (except pin 5) as input pins, the remote
command
GPIO:DIR is used. All pins (except pin 5) are represented
as 8-bits binary, according to Table 5 above. A “ 1” represents
OUTPUT, and a “0” represents INPUT. When using the GPIO:DIR
command, the decimal representation of the 8-bits binary is used.
For example, to set pins 7, 4, 2 and 1 as
INPUT pins, their values
must be set to 0, and the rest 1. Send:
GPIO:DIR 212
212 is used to represent11010100 in binary. Only pins 7, 4, 2, and 1
have the value “
0”, which represents INPUT.
Pin 9 8 7 6 5 4 3 2 1
1 1 0 1 - 0 1 0 0
To check the status of the input pins to be either 5 V (1) or 0 V (0),
use the
GPIO? query command. It will return the decimal
representation of the 8-bits binary that represents all the pins. The
pins with bit value “
1” have 5 V at the input, and “0” for 0 V at input.