10 VT1536A Isolated Digital Input/Output SCP
Programming With SCPI Commands
The SCPI commands shown here query the SCP's identification string, and
perform VT1536A channel configuration. The VT1415A/19A doesn't
provide SCPI commands to read an input channel or control an output
channel. Read and write operations are performed by the VT1415A/19A's
Algorithm language. See the following section for a digital input/output
example.

*RST & Power-up

Conditions The default configuration of the VT1536A at power-up or after a *RST
command is:
• Channel I/O direction is as set by the threshold/direction switches
(See “Setting Configuration Switches” on page 4.).
• Input and output channel polarity will be NORMal. This means:
-- For inputs; when the input opto isolator is be ing driven (is "on"), an
algorithm will read a logic 1. When the opto is off, the algorithm
reads a zero.
-- For outputs; when an algorithm writes a 1, the output relay will turn
on ("close"). Writing a zero will turn the relay off.
Remember, polarity NORMal means "1 = ON".
•Output configured channels will have their relays turned off ("open").

Checking the ID

of the SCP To verify the SCP type(s) installed on your VXI module, use the
SYSTem:CTYPE? (@<channel>) command.
•The channel parameter specifies a single channel in the channel range
covered by the SCP of interest. The first channel number for each of
the eight SCP positions are; 0,8,16,24,32,40,48, and 56.
The value returned for the VT1536A SCP is:
HEWLETT-PACKARD,E1536A Isolated Digital I/O SCP,0,0
To determine the type of SCP installed on channels 0 through 7 send
SYST:CTYPE? (@100) query SCP type @ ch 0
enter statement here enter response string

Determining Input

Threshold Level and

I/O Direction

The input threshold level and I/O direction is set (for each individual
channel) by hardware switches (See “Setting Configuration Switches” on
page 4.). To determine how a channel is currently configured, use the
command:
INPut:THReshold:LEVel? (@<channel>)
•Channel must specify a single channel