VXI VT1538A user manual Configuring I/O Direction, Setting the Input Threshold Level

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 E1538A SCP is:

HEWLETT-PACKARD,E1538A Enhanced Frequency/Totalize/PWM 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

Configuring the Channels

The E1538A has eight digital channels. The Power-on and *RST state is that all input-configured channels sense static digital state (SENS:FUNC:COND), and all output-configured channels output static digital state (SOUR:FUNC:COND). Logical sense is normal

(INP:POL NORM and OUTP:POL NORM).

Configuring I/O Direction

Programming Input Channels

Setting the Input

Threshold Level

Channels are configured for input or output with the I/O direction switches (see "Setting Configuration Switches" on page 6).

This section deals with all aspects of programming input channel functions. Channels are configured for input with the I/O direction switches (see "Configuring Input-Output direction" on page 6). A related error message: 3123,"E1538 OE switch ON conflicts with this command."

The E1538 allows programmatically setting the input threshold level for each input configured channel. The input threshold can be set from -46VDC to +46VDC with .375V resolution. While input polarity is set to NORMAL, an input level higher than the threshold level is considered a logic one, and an input level lower than the threshold level is considered a logic zero. If input polarity is set to INVerted, an input level higher than the threshold level is considered a logic zero and an input level lower than the threshold level is considered a logic one. To set input threshold level use the command

INPut:THReshold:LEVel <level>,(@<ch_list>)

•<level> is a value between -46 and +46 inclusive. The resolution for <level> is 0.375 Volts. The *RST and power-on default for <level> is 1.78 volts.

Note The value sent for <level> will be rounded to the nearest multiple of 0.375 Volts. For instance, 5 would be 4.875, 10 would be 10.125, 9.5 would be 9.375, and 15 would be 15. The INP:THR:LEV? query will return the actual setting.

12 Agilent E1538A Enhanced Frequency/Totalize/PWM SCP