Knowledge Base

TTL Port Tester

• Button 1/2 Presses. To base your condition on the number of presses of button 1 or 2 given since the activation of the condition. You can select either >= N, <= N, or = N. Enter the value N in the box.
• Is Button 1/2 Pressed? To base your condition on whether the button 1 or 2 is currently pressed. Select true or false from the list below.
• Is Light 1/2 On? To base your condition on whether the light 1 or 2 is currently on. Select true or false from the list below.

Beam Controller

• Beam 1/2 Breaks. To base your condition on the number of beam breaks for beam 1 or 2 since the activation of the condition. You can select either >= N, <= N, or = N. Enter the value N in the box.
• Is Beam 1/2 Broken? To base your condition on whether beam 1 or 2 is currently broken. Select True or False from the Signal value list.
• Is Cue 1/2 On? To base your condition on whether the cue 1 or 2 is currently on. Select true or false from the Signal value list.

Activity Wheel Counter

• Quarter Cycles. To base your condition on the number of quarter cycles since the activation of the condition. You can select either >= N, <= N, or = N. Enter the value N in the box.

Custom Hardware Device

This includes the illuminated shelter.

• Input 1/2 L/H -> H/L Count. To base your condition on how many times there has been a transition from High to Low (or vice versa) in input 1 or 2 during the time t-1 to t, where t is the sample time when the condition is evaluated. Choose the option that applies, select either >= N or <= N. Enter the value N in the box. This option lets you create a condition based on events (transitions) in the signal, no matter when they happen during the sample time.
• Is Input 1/2 High/Low? To base your condition on whether the current state of input 1 or 2 is High or Low at the sample time when the condition is evaluated. Select the option that applies, and then either true or false.
• Is Output 1/2 High? To base your condition on whether the current state of output 1 or 2 is High at the sample time when the condition is evaluated. Select the option that applies, and then either true or false. This option evaluates the state of the signal (High vs Low) at the sample time when the condition is evaluated. If a quick transition High -> Low -> High occurs within the sample interval, this is not noticed; the state at the sample time is still High.

Counts vs. Signals: Effects on Conditions

Consider the two conditions based on the same input (for example Input 1):

• Is the number of transitions H->L >= N?
• Is the state of the signal Low?

There is a fundamental difference between the two conditions.

In the first condition, the software counts the number of transitions from High to Low during the sampling interval (that is, from t-1 to t). The condition may become true or stay false for sample t, depending on that value.

In the second condition, the signal is evaluated at time t, that is, at the end of the sampling interval. If short transitions occur from High to Low to High again, the Low signal is not detected by this condition, because the signal is still High at time t.

Example Cases

The following cases illustrate how two conditions which may seem equivalent can give different results. The signal in each case represents the input from a hardware device, and the sample points represent evaluations in EthoVision XT:

1. The signal changes from High to Low. Both conditions are true at the time of evaluation.
2. The signal changes from High to Low to High within the sample time. The instance of Low is not detected by the condition based on the signal (Is Input Low?), because the signal value at the time of evaluation is High.
3. Similar to case 1.
4. Similar to case 2.

Source: EthoVision XT 18 - THC - Trial and Hardware Control, Noldus Information Technology