OpenDRO supports both Chinese and quadrature scales.
Chinese scales refer to any of a large number of linear scales and calipers that are sourced from China and based on capacitive sensing technology originally developed by Sylvac. These scales come in a huge variety of lengths and styles. Chinese scales usually have a four-pin output port on the side of the scale that sends the scale position data to the DRO. There are four different protocols used for sending this data:
In addition, the 24BIT and BCD7 scales support a "fast" mode where they send the data to the DRO at a much higher rate than normal. The 21BIT and BIN6 scales do not support that feature.
The metal backs of Chinese scales are connected to one of the battery terminals. For 24BIT and BCD7 scales, the metal backs are connected to the positive battery terminal. For 21BIT and BIN6 scales, the scale beams are connected to the negative battery terminal. If you mix both types on one DRO, then you must insulate them to avoid shorting the DRO power supply through the machine.
WARNING!!! Do not mix 21BIT or BIN6 scales with 24BIT or BCD7 scales without electrically isolating one scale type or the other.
Except for iGaging-branded 21BIT scales, it is difficult to determine which protocol a Chinese scale uses just by looking at it. You can differentiate between BIN6 and a 24BIT/BCD7 by using a multimeter to determine which side of the battery the scale back is connected to. Differentiating a BCD7 from a 24BIT is more difficult and is best done with an oscilloscope. Note, however, that 24BIT scales are much more common than BCD7 scales. Most of the time, you can set the scale type to "Auto" and OpenDRO will automatically detect and configure the scale type.
Quadrature scales are linear or rotary encoders that output two signals that are 90 degrees out of phase with each other and includes most glass scales encountered on machining equipment. OpenDRO supports any quadrature encoder that outputs a signal that is electrically compatible with the hardware it is running on. The DPU/DRO-550 supports quadrature encoders that output a digital, 5V output. A partial list of scale manufactures and their compatibility with the DPU/DRO-550 is shown in the following table.