Measurement Computing CB-7080 - Manual (Page 13)

CB-7080 & CB-7080D Counter/Timer User's Guide Application notes
1-9
Gate control setting
The gate control is ignored in frequency mode (51). The gate control is disabled in counter mode (50) by
default. To use a command to enable/disable the gate control:
 To use the $AAA0 command, the gate input must be low to enable the counter.
 To use the $AAA1 command, the gate input must be high to enable the counter.
 To use the $AAA2 command, the gate input is ignored. The counter is always enabled.
Preset value setting
The preset value is ignored in frequency mode (51). The counters go to their preset value in the first power-on
state. The reset counter command, $AA6N, also forces the counters to go to their preset value. The default
preset value is 0. Use the $AAPN(data) command to change the preset value. The key points include:
Table 1-5: Preset values
Factory default setting Counter preset value is 0
Power on state Counter 0/1 goes to preset value
$AA6N Counter N goes to preset value
$AAPN(data) Set preset value of counter N
Frequency input applications
The frequency mode type is indicated by entering 51in the command.
Table 1-6. Frequency mode settings
Command Result - Frequency 0 Result - Frequency 1
$AAB0 to set input mode 0
$AA1H(data) and $AA1L(data)
Non-isolated channel 0 and
threshold value active Non-isolated channel 1 and
threshold value active
$AAB1 to set input mode 1
$AA1H(data) & $AA1L(data)
Isolated channel 0 Isolated channel 1
$AAB2 to set input mode 2
$AA1H(data) & $AA1L(data)
Non-isolated channel 0 and
threshold value active Isolated channel 1
$AAB3 to set input mode 3
$AA1H(data) & $AA1L(data)
Isolated channel 0 Non-isolated channel 1 and
threshold value active
To measure frequency:
1. Use the $AA1H(data) and $AA1L(data) commands to set the threshold value, if the frequency is in a
non-isolated input.
2. Use the $AAB? command to select the mode (this command will clear the current frequency first).
3. Use the #AA? command to perform frequency measurement.
Only four commands are important in frequency measurement mode:
$AAB? Select mode
$AA1H(data) Set high-level threshold value
$AA1L(data) Set low-level threshold value
#AA? Perform frequency measurement
The status-read-back commands are:
$AAB? Mode read back
$AA1H High_level threshold value read back
$AA1L(data) Low_level threshold value read back