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What are the pulse input specifications for a MNB-series controller?

Issue

Customer is using UI1 of a MNB-300 and is missing an occasional pulse (approximately 1 %) when counting pulses from a water meter.

Environment

MNB-1000 (DI Inputs only)

MNB-300

MNB-70

MNB-V1

MNB-V2

Cause

High contact resistance / low open resistance or too short a pulse width.

Resolution

To detect a closed contact, the contact resistance must be less than 300 ohms.  If the contact resistance is greater than 300 ohms, the contact closure may not be detected.

To detect an open contact, the contact resistance must be greater than 2500 ohms.  If the open contact resistance (open circuit resistance) is less than 2500 ohms, the controller may not detect that the contact is open.

MNB-1000 DI1 - DI4  require a minimum contact closure duration of 50ms and a minimum contact open duration of 50ms.

MNB-300 UI1 require a minimum contact closure duration of 50ms and a minimum contact open duration of 50ms.

MNB-300 UI2 - UI6 require a minimum contact closure duration of 500ms and a minimum contact open duration of 500ms.

MNB-70 UI1 - UI3 require a minimum contact closure duration of 500ms and a minimum contact open duration of 500ms.

MNB-V1/V2 UI1 - UI3 require a minimum contact closure duration of 500ms and a minimum contact open duration of 500ms.

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Last update:
‎2018-09-06 12:14 PM
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