# DeltaV CHARM DEWD vs Linear Interpolation Master

The clearest difference is rating: Linear Interpolation Master at 4.7 against DeltaV CHARM DEWD's 4.1. Linear Interpolation Master also leads on ratings volume (176 vs 14) and device support (3 vs 1). DeltaV CHARM DEWD's advantage is in-app purchases (none vs 3) and ads (none vs shown). On price, review sentiment and update cadence there is nothing between them.

Both are free to download. Linear Interpolation Master sells 3 one-off in-app purchases. DeltaV CHARM DEWD asks for nothing beyond the download.

Linear Interpolation Master holds the better App Store score, 4.7 against 4.1. That said, the two scores are not equally well evidenced: Linear Interpolation Master has 176 ratings behind it against 14, so its average is the more settled of the two. Written reviews point the same way: 56% of DeltaV CHARM DEWD's written reviews are positive against 63% of Linear Interpolation Master's.

DeltaV CHARM DEWD ships an update every 4 months, Linear Interpolation Master every 5 months. The most recent releases landed on June 1, 2026 and September 22, 2026 respectively.

## The numbers

| Metric | DeltaV CHARM DEWD | Linear Interpolation Master |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.1 (14 ratings)](https://appshunter.io/ios/app/deltav-charm-dewd/id688891028/reviews) | **[4.7 (176 ratings)](https://appshunter.io/ios/app/linear-interpolation-master/id1433976994/reviews)** |
| Number of ratings | 14 | **176** |
| Positive reviews | 55.6% of reviews | **62.5% of reviews** |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | **Every 4 months** | Every 5 months |
| Monetization | **Free** | Free with in-app purchases |
| Size | 64 MB | 16 MB |
| Requires iOS | 16.0 | **11.0** |
| Devices | iPhone | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Emerson Process Management](https://appshunter.io/developer/561985742) | [VERVE TECHNOLOGIES PTY. LTD.](https://appshunter.io/developer/582523354) |

## What reviewers say

### DeltaV CHARM DEWD

[App page](https://appshunter.io/ios/app/deltav-charm-dewd/id688891028)

Diagnose and wire DeltaV CHARMs using your mobile device's camera. Scan CHARM LEDs to understand blink patterns or scan labels for wiring diagrams. Quickly access information, save favorites, add notes, and share with colleagues.

**Highlights:** Scan CHARM LED blink patterns, Scan CHARM labels for text recognition, Instantly understand blink pattern meanings, Swiftly find associated wiring diagrams, Browse and search for results, Store results as Favorites, Create or edit Notes, Share information with colleagues

**Features:** macOS Compatibility

**In-app purchases:** none


### Linear Interpolation Master

[App page](https://appshunter.io/ios/app/linear-interpolation-master/id1433976994)

This tool simplifies linear interpolation calculations for industrial commissioning engineers. It features large, easily readable numbers for field use and allows for quick swapping of coordinate systems, such as converting between 4-20mA and 0-100% scales.

**Highlights:** Large number display for field visibility, Quickly swap X and Y coordinates, 4-20mA to 0-100% conversion, 0-100% to 4-20mA conversion

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Generous Tip | $2.99 | one-time |
| Massive Tip | $3.99 | one-time |
| Amazing Tip | $4.99 | one-time |


## Frequently asked questions

### Is DeltaV CHARM DEWD free?

DeltaV CHARM DEWD is free to download, with no in-app purchases.

### Is Linear Interpolation Master free?

Linear Interpolation Master is free to download, with in-app purchases available.

### Which has better reviews, DeltaV CHARM DEWD or Linear Interpolation Master?

Linear Interpolation Master is rated higher. DeltaV CHARM DEWD averages 4.1 out of 5 from 14 ratings, while Linear Interpolation Master averages 4.7 from 176 ratings.

### Do DeltaV CHARM DEWD or Linear Interpolation Master have ads?

Linear Interpolation Master shows ads; DeltaV CHARM DEWD does not.

### Which is updated more often, DeltaV CHARM DEWD or Linear Interpolation Master?

DeltaV CHARM DEWD ships an update every 4 months, and Linear Interpolation Master every 5 months. Most recently, DeltaV CHARM DEWD was updated on June 1, 2026 and Linear Interpolation Master on September 22, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*