ModTest Pro vs Grindcalculator
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
ModTest Pro
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MODTest Pro is a fast and simple utility for testing MODBUS devices over WiFi or Bluetooth. It supports a wide range of MODBUS functionality, including the ability to operate as a client or server (master or slave). It supports both TCP and UDP connections when using WiFi and it supports serial communication via many BLE modules equipped with Bluetooth 4 or higher that provide UART bridging capability. Tap the Setup button to enter the appropriate parameters for your device. Return to the main display to send your poll and view the data (when in client mode) or accept and respond to data requests from a master device (when in server mode). The Comm Setup view allows a number of addressing, timing, and communication mode parameters to be configured. Besides a comprehensive user guide, the app also has extensive built-in help. Tap on any yellow label or info button for a description of that parameter. The app supports MODBUS-TCP, -RTU, and -ASCII protocols, and they can all be transmitted via TCP, UDP, or Bluetooth. It also supports the GSI protocol which was developed in 1985 and was the first tank gauging protocol to use standard RS232/RS485 serial data communication. The app also features a User Data Mode that allows you to enter a complete poll string independent of any particular protocol. This allows transmission of special ASCII data polls or any MODBUS command that is not natively supported by the app. The following MODBUS function codes are supported: 1 – Read Coils 2 – Read Discrete Inputs 3 – Read Holding Registers 4 – Read Input Registers 5 – Write Single Coil 6 – Write Single Register 7 – Read Exception Status 15 – Write Multiple Coils 16 – Write Multiple Registers 17 – Report Server ID Addresses must be entered in standard MODBUS format (0-65535). If you are accustomed to specifying register addresses in "Modicon format", simply subtract 1 from the Modicon Address and delete the prefix number. For example, Modicon Holding Register 40101 is equivalent to MODBUS address 100. The app supports a wide range of data representations including: Unsigned Integer: 16 bit, 32 bit, and 64 bit Signed Integer: 16 bit, 32 bit, and 64 bit Floating Point: 32-bit, and 64-bit using IEEE-754 specifications Hex Data Strings: 16-bit, 32 bit, and 64-bit Bit and Byte Representations for Coils & Discrete Inputs The app also supports the following "reverse modes" of floating point data storage: Atomic 8-bit Little Endian Atomic 16-bit Little Endian PDP Endian Bit Reversal When you exit the Comm Setup page, WiFi connections will be established automatically; however, a manual scan must be initiated to find and select a BLE module within range in order to establish a Bluetooth connection. After a successful Wifi or BLE connection, simply tap the Start Poll button to send your poll command (when in client mode). Continuous polling is also supported. When in server mode, the app will wait for and respond to poll requests from a master device once a WiFi or BLE connection is made. The app scans for UART Service & TX/RX Characteristic UUIDs from BLE devices by a number of manufacturers. The UUIDs that are supported are detailed in the app User Guide. A communication status window will show the raw byte strings that are sent to and received from a remote device. Received data will also be shown in tabular form when in client mode and communication events will be shown when in server mode. The app also tracks a number of communication statistics. When using WiFi your device must be on the network as the device that you want to test. Be sure to use the Settings app to configure your network settings before using the app or you will surely get socket connection errors. The app contains no ads or in-app purchases and we will never nag you for reviews, although we do appreciate them. If you have any issues with the app, please send us a message before posting a negative review and give us a chance to address your concerns.
Grindcalculator
This tool simplifies knife sharpening by calculating the correct angle, eliminating the need for manual marking. Save custom sharpening angles and grinding wheel dimensions for consistent results across various brands and types of sharpening tools.
- Precise angle calculation
- Eliminates manual marking
- Save custom angles
- Save grinding wheel dimensions
- Supports all grinder brands
- Offline functionality
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The sharpening calculator is the perfect tool for sharpening knives. Especially when sharpening knives, it is important that the correct angle is resharpened. Most manufacturers, such as Tormek, Einhell, Scheppach, Record Power and many others supply an angle gauge specially designed for the machine. It takes a lot of practice to set the machine correctly with the gauge in order to be able to sharpen the correct sharpening angle on the knife or any other sharpening piece. Professionals often mark their phase to adjust the toolbar to the correct height. We developed the sharpening calculator app to make it easier to sharpen or sharpen knives and, above all, to get a consistently good sharpening result. The annoying phase marking is no longer necessary. Just like the complicated application of the angle gauge to the clamped sanding pad and the adjustment of the toolbar. There is almost no limit to the detection of grinders, grinding wheels and grinding pieces. Grinding pieces are, for example, kitchen knives, wood chisels or planer knives. Everything that can be ground with a wet grinding machine. After the app has been installed, the basic dimensions for the top toolbar, the front bar and, if available, the front base must be entered as described in our tutorial. The values can be adjusted at any time if you have measured yourself. The grinding wheels can either be saved or adjusted again for each grinding process. Here it is important that CBN wheels, for example, always have the same diameter, but wet grinding stones lose diameter through use. This value must be adjusted before grinding. The grinding calculator is suitable for probably every grinding machine from all manufacturers. Even individual structures can be used. Many app users have bought various grinding wheels from, for example, grinding junkies. The grinding calculator also works perfectly for this. With some polishing wheels, an angle correction can be stored so that polishing works even better. If you have recurring sharpening pieces such as kitchen knives, it is possible to save them with the respective sharpening angle. This eliminates the need to measure the angle again when resharpening and everything goes much faster. The grinding calculator is now also available for the iPad. All functions can be used. If you allow access to the iCloud, then all entries are synchronized between the devices. This means that all devices, grinding wheels and grinding pieces are synchronized on all devices used such as iPhone and iPad. This process is also the only thing for which the grinding computer needs an internet connection. Otherwise, the app works anytime, anywhere, even without an active internet connection. With family sharing, each user has their own database. It is currently not possible to share your own devices between users. Further features are described on our website https://www.grindcalculator.de. The procedure is described in detail in the operating instructions, which can be found under the URL https://www.grindcalculator.de/tutorials/operation-manual.
Screenshots
Verdict
The clearest difference is update cadence: Grindcalculator at every 4 days against ModTest Pro's every 2 months. Grindcalculator also leads on price ($6.99 vs $9.99). ModTest Pro's advantage is iOS requirement (13.0 vs 26.0). On ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
ModTest Pro costs $9.99 and Grindcalculator $6.99 up front. Neither carries in-app purchases, so what you see is what you pay.
ModTest Pro ships an update every 2 months, Grindcalculator every 4 days. The most recent releases landed on October 31, 2026 and November 3, 2026 respectively.
| Parameter | ModTest Pro | Grindcalculator |
|---|---|---|
| Price | $9.99 | $6.99 — better |
| Rating | — | 1.0 (1 ratings) — better |
| Positive reviews | — | 84.6% of reviews |
| Number of ratings | — | 1 — better |
| Update frequency | Every 2 months | Every 4 days — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | — | Paid |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 13.0 — better | 26.0 |
| Further details — not scored | ||
| Size | 26 MB | 9 MB |
| Age rating | 4+ | 4+ |
| Developer | Dohmann Engineering Services | RoWo UG |
In-app purchases
ModTest Pro
No in-app purchases
Grindcalculator
No in-app purchases









