Быстродействие при обмене данными/en — различия между версиями
(Новая страница: «Because the test is synthetic, we tried to get most out of the PLC and WebHMI to achieve the best result. For this, we reduced the filtering time from bounce to t…») |
(Новая страница: «With this configuration (reading only one register X0), the average time of the WebHMI scan was 7ms on average.») |
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| − | + | With this configuration (reading only one register X0), the average time of the WebHMI scan was 7ms on average. | |
Ниже приведен скриншот испытания с временными метками. | Ниже приведен скриншот испытания с временными метками. | ||
Версия 22:02, 31 октября 2017
How quickly WebHMI can respond to external events?
To answer this question, we have assembled a test bench. The bench consisted of WebHMI, Delta Electronics DVP-14SS2 controller, logic analyzer and a button. The button is connected to the X0 input of the PLC. The PLC duplicates the state of the button on the Y3 output. WebHMI reads X0 status using the ModBus RTU protocol (115200, 8E1) and when changing the value X0 writes it to Y2. The logic analyzer is connected to all signals (X0, Y2, Y3) and allows measuring the reaction time with high accuracy.
Thus, in Y3, the input X0 is displayed using the internal program of the PLC, and in Y2 - using the WebHMI program.
Because the test is synthetic, we tried to get most out of the PLC and WebHMI to achieve the best result. For this, we reduced the filtering time from bounce to the PLC (register D1020) from 10ms to 0ms. Also, we switched the Y2 register to the Read On Demand mode in order not to waste time reading its value. It only writes to it, so we do not need to read it in this example.
With this configuration (reading only one register X0), the average time of the WebHMI scan was 7ms on average.
Ниже приведен скриншот испытания с временными метками.
Здесь видно, что ПЛК реагирует на нажатие кнопки примерно за 4.9мс, а WebHMI - за 15.9 мс. Это время между возникновением электрического сигнала на входе ПЛК и возникновением ответного сигнала на выходе ПЛК.
Таким образом, при подключении к ПЛК на скорости 115200 в идеальных условиях можно получить время реакции WebHMI на внешние воздействия порядка 16мс.
