---
title: "readAttributeRmsVoltageSag(completionHandler:)"
framework: matter
role: symbol
role_heading: Instance Method
path: "matter/mtrbaseclusterelectricalmeasurement/readattributermsvoltagesag(completionhandler:)"
---

# readAttributeRmsVoltageSag(completionHandler:)

## Declaration

```swift
func readAttributeRmsVoltageSag(completionHandler: @escaping @Sendable (NSNumber?, (any Error)?) -> Void)
```

```swift
func readAttributeRmsVoltageSag() async throws -> NSNumber
```