TouchDRO Adapter Feature Comparison

The new ESP32-based TouchDRO Scale adapters have replaced the previous generation of pre-assembled MSP430-based adapters. Since the ESP32 microcontroller architecture is much more powerful and flexible, the new adaptes have some additional capabilities compared to the DIY kits and the old adapters. Among other things, support for a wider variety of scale protocols. As a result, there is some overlap between the three adapter versions but since the adapters are optimized to work with a specific type of scales, they offer slightly different features.

TouchDRO Adapter Features

Adapter for iGaging Scales Adapter for Shahe Scales Adapter for Glass/Magnetic Scales
Details link link link
Position Refresh Rate 10Hz capacitive scales
20Hz glass scales*
10Hz capacitive scales
20Hz glass scales*
25Hz
Supply Voltage 3.6V-5.5V 3.6V-5.5V 5V-5.5V
Max Current Draw 500mA 500mA 300mA
Firmware Family ESP32 Capacitive Scales ESP32 Capacitive Scales ESP32 Quadrature
Scale Inputs
Min Signal Voltage 2V 1.2V 1.8V
Max Signal Voltage 3.3V 5V 5V
Max Low Signal Voltage 1V 0.6V 1.2V
Scale Supply Voltage  
5 Vscale Yes Yes Yes
3.3 Vscale Yes Yes Yes
1.8 Vscale No Yes No
Vscale Battery Backup 3.3V 3.3V/1.8V No
Tachometer Input  
Pulses/Second 0.5-10,000 0.5-10,000 0.5-10,000
Min Signal Voltage 2V 2V 2V
Max Signal Voltage 3.3V 3.3V 5V
Max Low Signal Voltage 1V 1V 1V
Supply Voltage 3.3V 3.3V 5V
Pull up/down 3.3V 3.3V 5V
Probe Input
Min Signal Voltage 2V 2V 2V
Max Signal Voltage 3.3V 3.3V 5V
Max Low Signal Voltage 1V 1V 1V
Supply Voltage 3.3V 3.3V 5V
Pull up/down 3.3V 3.3V 5V
Max Trigger Delay 100ms w/capacitive scales
<1us w/glass scales
100ms w/capacitive scales
<1us w/glass scales
<1us w/glass scales
Limit Switch Inputs No No Yes
Min Signal Voltage N/A N/A 2V
Max Signal Voltage N/A N/A 5V
Max Low Signal Voltage N/A N/A 1V
Supply Voltage N/A N/A 5V
Pull up/down N/A N/A 5V
Max Trigger Delay N/A N/A <1us w/glass scales

*Starting with firmware version 1.2 (units shipped after July 1, 2021)

Position Refresh Rate

This is the frequency at which the given adapter sends the value to the application when the axis is in motion. For instance, the adapter from glass/magnetic scales will send the position 25 times per second, while the other two send the value only 10 times per second.

Tachometer Pulses Per Second

This is the number of pulses per second the tachometer can recognize reliably. For instance, when a single mark encoder disk is used, the tachometer will read between 30 RPM and 600,000 RPM (1 pulse every 2 seconds to 10,000 pulses per second); with a disk that has 10 marks, the supported RPM range will be between 3RPM and 60,000 RPM.

Probe and Limit Switch Trigger Delay

This is the amount of time the adapter will take to capture the position after the probe or a limit switch is engaged. This is proportional to the potential digital "backlash" in the system. For instance, when the axis is moving at 1mm per second, 1us delay will result in potential error of 0.000001mm; 100ms will result in 0.1mm potential error.

Max Signal Voltage

This is the highest safe signal level that can be applied to the given input. Voltage that is higher than the indicated level will quickly permanently damage the input and the board will need to be repaired.

Min Signal Voltage

This is the lowest voltage level that will be recognized by the given input. Any value above this level (up to the max voltage) will be treated as a logical 1.

Max Low Signal Voltage

This is the highest voltage level that will still be recognized as a logical 0 when the signal is going from high-to-low.

Supported Scales

Between the three new adapter versions, it's now possible to use the following scales with TouchDRO:

Each TouchDRO adapter hardware is designed and optimized to achieve best performance with a specific set of scales. For instance, the adapters for Shahe and iGaging scales come with Mini- and Micro-USB connectors pre-wired for the particular scales. That said, the hardware and the firmware is capable of supporting other scale types with some minor modifications. In some cases, modification is limited to the wiring of a custom connector. Other scales might require additional pull up or down resistors or level conversion circuits.

Please refer to Using Quadrature Encoders with Capacitive Scale TouchDRO Adapters for more information about connecting supported quadrature encoders to the capacitive scale TouchDRO adapters.

In the table below the following convention will be used:

Adapter for iGaging Scales Adapter for Shahe Scales Adapter for Glass/Magnetic Scales
Supported Protocols
Quadrature Yes 1 Yes Yes
iGaging 21-Bit Yes No 2 No
iGaging Absolute Yes Yes No
BIN6 Yes Yes No
Quadrature Encoders
Glass/Magnetic Scales 3.3V Direct PnP
NPN Encoders Direct Direct Direct 3
PNP Encoders No No Direct 4
Push/Pull Encoders 3.3V Direct Direct
Capacitive Scales
iGaging EZ-View DRO Plus PnP No 2 No
iGaging DigiMag Remote DRO (Micro-USB) PnP No 2 No
iGaging DigiMag Remote DRO (Mini-USB)
AccuRemote DRO (Mini-USB)
Shars Digital Machine Aluminum Scale (Mini-USB)
PnP 5 No 2 No
iGaging Absolute DRO Plus (Micro-USB) PnP Direct No
iGaging Absolute DRO Plus (Mini-USB) Direct Direct No
Shahe Remote DRO Display (5403 series)
Machine-DRO M-Sure MS-278
Direct PnP No
Shahe Vertical Linear Scale (5401 series) No Direct No

1 Starting with firmware version 1.1 (orders shipped starting June 1st, 2021)
2 The protocol is supported but the adapter doesn't provide the clock signal, so it can only be used if connected in parallel with the native display
3 A pull-up resistor is recommended for better noise resiliency
4 A pull-dow resistor is required
5 With a Mini-USB Male to Micro-USB Female Adapter