Table of Contents

Examples

You can find the following examples of math formula use on this page:

Logic Functions

The result of logic operators is always 0 or 1. We will use this fact in the following equation:

dwsmath-jure_sl01_exam_log-formula

The first part of the equation will return 1 when the input channel ‘sinus’ is positive and the value of 0 when the sinus will be negative. Multiplying this result with the original signal will result in cutting the negative part of the signal.

dwsmath-jure_sl02_exam_log-signal

Signals

The signal generator is used for making a test signal for testing. We have basic functions like a sine wave, square, triangle, rectangle and noise. We can define also the phase for each individual channel. The phase is defined in radians, so in the example below the sine wave with 1 Hz frequency and 180 deg phase is defined.

dwsmath-jure_sl05_exam_signal-formula

The example above results in the following signals:

dwsmath-jure_sl06_exam_signal-signal

To generate signals with variable frequencies, it is better to use function generator in Analog out section. The Test AO is free of charge and can produce signals with variable frequencies, amplitudes and phases.

Measure Functions

The following example shows the measurement of the pulsewidth. Let’s say that the input is a square wave and we want to measure the pulse width of this channel. First of all, we need to translate the input signal in the logic with ‘F1’>0. This will give a value of 1 for positive and value of zero for negative values of the input signal. The pulsewidth function will then measure the time between each transition. If we want to measure the frequency, we can calculate the inverse of this function as seen below.

dwsmath-jure_sl07_exam_measfunc-formula

The graph shows a pulse width measurement (Math0) and frequency measurement (Math1).

dwsmath-jure_sl08_exam_measfunc-signal

‘pulsewidth’ function is useful for digital signal. The resolution of the measurement is limited by the sample rate.

If we want to measure the pulse width or frequency of sine waves, it is better to use Exact frequency math module, described in the following chapters.

Stopwatch

There are two functions in Measure section of math which helps to measure time and value between events. The Stopwatch functions enable us to measure the time between a start and stop event. The ‘measdiff’ function makes the same measurement, but we can define the measurement channel instead of time.

In the example shown we measure the brake time and brake distance. The first example gives the time of braking between 60 km/h and 2 km/h.

The second channel measures the distance between 60 and 2 km/h. This is achieved by defining the Distance channel as the calculated value.

dwsmath-jure_sl09_exam_stopwatch-formula

The graph below shows the example of measured data - input channels of velocity and distance. The meter shows the time and distance of braking.

dwsmath-jure_sl10_exam_stopwatch-signal

Dewesoft 7 interpolates the velocity and distance channels. So for examples if measured velocity points are 61.2 and 59.2, it will take the time in between those two values as the start trigger.

Input Events

The input events combined with count procedures are very useful for counting events (for example event counting).

dwsmath-jure_sl03_exam_events-formula

The example above counts up when the right cursor key is pressed and counts down when the left cursor key is pressed.

dwsmath-jure_sl04_exam_events-signal

The Keypressed option in formula uses the virtual key codes.

Symbolic constant name Value(decimal) Mouse or keyboard equivalent
VK_LBUTTON 1 Left mouse button
VK_RBUTTON 2 Right mouse button
VK_CANCEL 3 Control-break processing
VK_MBUTTON 4 Middle mouse button (three-button mouse)
VK_XBUTTON1 5 Windows 2000: X1 mouse button
VK_XBUTTON2 6 Windows 2000: X2 mouse button
— 7 Undefined
VK_BACK 8 BACKSPACE key
VK_TAB 9 TAB key
— 10–11 Reserved
VK_CLEAR 12 CLEAR key
VK_RETURN 13 ENTER key
— 14–15 Undefined
VK_SHIFT 16 SHIFT key
VK_CONTROL 17 CTRL key
VK_MENU 18 ALT key
VK_PAUSE 19 PAUSE key
VK_CAPITAL 20 CAPS LOCK key
VK_KANA 21 IME Kana mode
VK_HANGUEL 21 IME Hanguel mode (maintained for compatibility; use VK_HANGUL)
VK_HANGUL 21 IME Hangul mode
— 22 Undefined
VK_JUNJA 23 IME Junja mode
VK_FINAL 24 IME final mode
VK_HANJA 25 IME Hanja mode
VK_KANJI 25 IME Kanji mode
— 26 Undefined
VK_ESCAPE 27 ESC key
VK_CONVERT 28 IME convert
VK_NONCONVERT 29 IME nonconvert
VK_ACCEPT 30 IME accept
VK_MODECHANGE 31 IME mode change request
VK_SPACE 32 SPACEBAR
VK_PRIOR 33 PAGE UP key
VK_NEXT 34 PAGE DOWN key
VK_END 35 END key
VK_HOME 36 HOME key
VK_LEFT 37 LEFT ARROW key
VK_UP 38 UP ARROW key
VK_RIGHT 39 RIGHT ARROW key
VK_DOWN 40 DOWN ARROW key
VK_SELECT 41 SELECT key
VK_PRINT 42 PRINT key
VK_EXECUTE 43 EXECUTE key
VK_SNAPSHOT 44 PRINT SCREEN key
VK_INSERT 45 INS key
VK_DELETE 46 DEL key
VK_HELP 47 HELP key
  48 0 key
  49 1 key
  50 2 key
  51 3 key
  52 4 key
  53 5 key
  54 6 key
  55 7 key
  56 8 key
  57 9 key
— 58–64 Undefined
  65 A key
  66 B key
  67 C key
  68 D key
  69 E key
  70 F key
  71 G key
  72 H key
  73 I key
  74 J key
  75 K key
  76 L key
  77 M key
  78 N key
  79 O key
  80 P key
  81 Q key
  82 R key
  83 S key
  84 T key
  85 U key
  86 V key
  87 W key
  88 X key
  89 Y key
  90 Z key
VK_LWIN 91 Left Windows key (Microsoft® Natural® keyboard)
VK_RWIN 92 Right Windows key (Natural keyboard)
VK_APPS 93 Applications key (Natural keyboard)
— 94 Reserved
VK_SLEEP 95 Computer Sleep key
VK_NUMPAD0 96 Numeric keypad 0 key
VK_NUMPAD1 97 Numeric keypad 1 key
VK_NUMPAD2 98 Numeric keypad 2 key
VK_NUMPAD3 99 Numeric keypad 3 key
VK_NUMPAD4 100 Numeric keypad 4 key
VK_NUMPAD5 101 Numeric keypad 5 key
VK_NUMPAD6 102 Numeric keypad 6 key
VK_NUMPAD7 103 Numeric keypad 7 key
VK_NUMPAD8 104 Numeric keypad 8 key
VK_NUMPAD9 105 Numeric keypad 9 key
VK_MULTIPLY 106 Multiply key
VK_ADD 107 Add key
VK_SEPARATOR 108 Separator key
VK_SUBTRACT 109 Subtract key
VK_DECIMAL 110 Decimal key
VK_DIVIDE 111 Divide key
VK_F1 112 F1 key
VK_F2 113 F2 key
VK_F3 114 F3 key
VK_F4 115 F4 key
VK_F5 116 F5 key
VK_F6 117 F6 key
VK_F7 118 F7 key
VK_F8 119 F8 key
VK_F9 120 F9 key
VK_F10 121 F10 key
VK_F11 122 F11 key
VK_F12 123 F12 key
VK_F13 124 F13 key
VK_F14 125 F14 key
VK_F15 126 F15 key
VK_F16 127 F16 key
VK_F17 128H F17 key
VK_F18 129H F18 key
VK_F19 130H F19 key
VK_F20 131H F20 key
VK_F21 132H F21 key
VK_F22 133H F22 key
VK_F23 134H F23 key
VK_F24 135H F24 key
— 136–143 Unassigned
VK_NUMLOCK 144 NUM LOCK key
VK_SCROLL 145 SCROLL LOCK key
  146–150 OEM specific
— 151–159 Unassigned
VK_LSHIFT 160 Left SHIFT key
VK_RSHIFT 161 Right SHIFT key
VK_LCONTROL 162 Left CONTROL key
VK_RCONTROL 163 Right CONTROL key
VK_LMENU 164 Left MENU key
VK_RMENU 165 Right MENU key
VK_BROWSER_BACK 166 Windows 2000: Browser Back key
VK_BROWSER_FORWARD 167 Windows 2000: Browser Forward key
VK_BROWSER_REFRESH 168 Windows 2000: Browser Refresh key
VK_BROWSER_STOP 169 Windows 2000: Browser Stop key
VK_BROWSER_SEARCH 170 Windows 2000: Browser Search key
VK_BROWSER_FAVORITES 171 Windows 2000: Browser Favorites key
VK_BROWSER_HOME 172 Windows 2000: Browser Start and Home key
VK_VOLUME_MUTE 173 Windows 2000: Volume Mute key
VK_VOLUME_DOWN 174 Windows 2000: Volume Down key
VK_VOLUME_UP 175 Windows 2000: Volume Up key
VK_MEDIA_NEXT_TRACK 176 Windows 2000: Next Track key
VK_MEDIA_PREV_TRACK 177 Windows 2000: Previous Track key
VK_MEDIA_STOP 178 Windows 2000: Stop Media key
VK_MEDIA_PLAY_PAUSE 179 Windows 2000: Play/Pause Media key
VK_LAUNCH_MAIL 180 Windows 2000: Start Mail key
VK_LAUNCH_MEDIA_SELECT 181 Windows 2000: Select Media key
VK_LAUNCH_APP1 182 Windows 2000: Start Application 1 key
VK_LAUNCH_APP2 183 Windows 2000: Start Application 2 key
— 184-185 Reserved
VK_OEM_1 186 Windows 2000: For the US standard keyboard, the ‘;:’ key
VK_OEM_PLUS 187 Windows 2000: For any country/region, the ‘+’ key
VK_OEM_COMMA 188 Windows 2000: For any country/region, the ‘,’ key
VK_OEM_MINUS 189 Windows 2000: For any country/region, the ‘-’ key
VK_OEM_PERIOD 190 Windows 2000: For any country/region, the ‘.’ key
VK_OEM_2 191 Windows 2000: For the US standard keyboard, the ‘/?’ key
VK_OEM_3 192 Windows 2000: For the US standard keyboard, the ‘~’ key
— 193–215 Reserved
— 216–218 Unassigned
VK_OEM_4 219 Windows 2000: For the US standard keyboard, the ‘[{’ key
VK_OEM_5 220 Windows 2000: For the US standard keyboard\, the ‘\|’ key
VK_OEM_6 221 Windows 2000: For the US standard keyboard, the ‘]}’ key
VK_OEM_7 222 Windows 2000: For the US standard keyboard, the ‘single-quote/double-quote’ key
VK_OEM_8 223
— 224 Reserved
  225 OEM specific
VK_OEM_102 226 Windows 2000: Either the angle bracket key or the backslash key on the RT 102-key keyboard
  227–228 OEM specific
VK_PROCESSKEY 229 Windows 95/98, Windows NT 4.0, Windows 2000: IME PROCESS key
  230 OEM specific
VK_PACKET 231 Windows 2000: Used to pass Unicode characters as if they were keystrokes. The VK_PACKET key is the low word of a 32-bit Virtual Key value used for non-keyboard input methods. For more information\, see Remark in KEYBDINPUT\, SendInput\, WM_KEYDOWN\, and WM_KEYUP
— 232 Unassigned
  233–245 OEM specific
VK_ATTN 246 Attn key
VK_CRSEL 247 CrSel key
VK_EXSEL 248 ExSel key
VK_EREOF 249 Erase EOF key
VK_PLAY 250 Play key
VK_ZOOM 251 Zoom key
VK_NONAME 252 Reserved for future use
VK_PA1 253 PA1 key
VK_OEM_CLEAR 254 Clear key