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

# readAttributeRmsVoltageSag(completion:)

## Declaration

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

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