{"id":1235,"date":"2017-10-18T15:31:09","date_gmt":"2017-10-18T21:31:09","guid":{"rendered":"https:\/\/scadametrics.com\/blog\/?p=1235"},"modified":"2022-10-15T15:59:30","modified_gmt":"2022-10-15T21:59:30","slug":"new-improved-digital-de-bounce-algorithm-added-to-ethermeter","status":"publish","type":"post","link":"https:\/\/scadametrics.com\/blog\/?p=1235","title":{"rendered":"New Improved Digital Pulse De-Bounce Algorithm for EtherMeter!"},"content":{"rendered":"
\"James

Jim ‘Slim’ Mimlitz, SCADAmetrics<\/p><\/div>\n

Although the EtherMeter\u00ae<\/strong> is designed primarily as a SCADA gateway for water meters equipped with absolute encoder signals, it also provides support for dry-contact pulse output flow meters<\/strong>.\u00a0 These can include gas meters, electric meters, water meters, wastewater meters, steam meters, hot water meters, and many others<\/strong>.<\/p>\n

When interfacing with mechanical pulse meters, a common challenge is handling “Contact Bounce”<\/strong>.\u00a0 For example, after a certain volume of gas flows through a meter, the meter provides a single, brief contact closure. A contact closure event might have a duration of 50 milliseconds (typical), but it may also be shorter or longer in duration, as well.\u00a0 The contact closure could be in the form of a “solid-state” contact (a Transistor\u00a0 Switch), or it could be in the form of a “mechanical” contact (a Reed Relay Switch).<\/p>\n

When a mechanical Reed Relay switch closes, it may physically “bounce” during the make and break movements, which can be interpreted by sensitive instrumentation as multiple contact closures, instead of one, as intended.\u00a0 This can introduce significant over-counting errors into the monitoring system, unless properly handled through “De-Bouncing”<\/strong>.<\/p>\n

\"\"<\/a>

In this illustration, the raw, jittery pulse signal will likely be interpreted as 8 pulses. The digitally-debounced signal, however, will be correctly interpreted as 2 pulses.<\/p><\/div>\n

“De-Bouncing”<\/strong>\u00a0describes the process of sensing the intended contact closure signal, while filtering out the extra, unintentional contact closures.<\/p>\n

De-Bouncing can be implemented in hardware<\/strong>, by using resistors and a capacitor to form a low-pass filter.\u00a0 De-Bouncing can also be implemented in the EtherMeter’s\u00a0software<\/strong>, by using high-speed sampling and signal processing algorithms.<\/p>\n

Several years ago, SCADAmetrics introduced its first-generation, software-based De-Bounce Algorithm into the EtherMeter to provide an alternative to the resistor\/capacitor hardware-based solution.<\/p>\n

Today, SCADAmetrics is pleased to introduce its second-generation, software-based De-Bounce Algorithm.\u00a0 The new algorithm analyzes incoming meter pulses against the user setting “DEBOUNCE_MS”, and accumulates the pulse count according to the logic described below.<\/p>\n

\"\"<\/a>

Illustration of How the EtherMeter Can De-Bounce a Jittery Pulse Input with a Software Algorithm.<\/p><\/div>\n

When the DEBOUNCE Algorithm is ACTIVATED, then the following logic applies:<\/strong><\/span><\/p>\n

If the CONTACT has been OPEN continuously for DEBOUNCE_MS (or more)...\nAND...\nThe CONTACT is detected to transition to CLOSED...\nTHEN...\nThe Pulse Count will INCREMENT BY ONE.\n\nAvailable De-Bounce Setting: 1ms <= DEBOUNCE_MS <= 500ms<\/pre>\n
When the DEBOUNCE Algorithm is DEACTIVATED, then the following logic applies:<\/strong><\/span><\/p>\n
If the CONTACT has been OPEN continuously for 208 usec (or more)...\nAND...\nThe CONTACT is detected to transition to CLOSED...\nTHEN...\nThe Pulse Count will INCREMENT BY ONE.\n\nThe EtherMeter will count pulses as fast as it can detect them:\n2400 pulses-per-second, maximum.<\/pre>\n