In this article, a digital counter display manufactured and sold by CNL Devices Inc. will be reviewed. It was originally designed to be used with rotary or linear incremental encoders to display position readings, but the programmability of the display makes it readily adaptable to other applications as well.
For example, the display could be used to display speed or event counts. And with some factory hardware modifications, it could be used with other types of sensors to display such things as temperature, pressure, sound level, voltage, current, and so on.
Two LED Displays In One Unit
The display unit is actually two 4-digit LED displays in one. Except for sharing a common power supply, the two displays operate independently of one another.
Each of the two displays can be programmed to readout in different units of measurement. One could be used with an incremental rotary encoder to read out in degrees of rotation or speed of rotation while the other display could be used with an incremental linear encoder to read out in inches.
Each LED digit is made up of 7 segments displaying the numerals zero through nine (0-9), and a decimal point segment. The height of each of the high brightness and high contrast digits is 0.28 inch (7.0 mm). The 4-digit LED displays are available in red light or green light colors, and the top and bottom displays can match in color or one can be red and the other green.
Preset Button For Top And Bottom Displays
On the front of the display unit are two white “PRESET” buttons. One is for the top display and the other for the bottom display. The buttons are factory programmable to set the value being displayed to zero or some customer specified preset value.
Also, when the display is first powered on, it will either reset to zero or preset to some factory programmed value as specified by the customer.
Two Input Connectors, Power Jack, And On/Off Switch On Back
Located on the back of the display unit are two 5-pin male connectors for bringing in the signals from incremental encoders or other sensors. The connectors are Molex type with a finger-latching locking feature, and the pin spacing is 0.1″ center-to-center.
When using the display unit with incremental encoders, the pin-out of the 5-pin connectors is:
Pin 1 – Ground
Pin 2- Not Used
Pin 3 – Channel A
Pin 4 – +5V Power
Pin 5 – Channel B
A round 2.1 mm DC power jack is also located on the back of the display where the customer can supply their own local source of DC power to the display unit or a power supply can be purchased along with the display unit from CNL Devices Inc. The display unit can be powered with any regulated dc voltage in the range of 7 to 36 volts.
There is a power on/off slide switch also located on the back of the display unit.
The Display Unit In Action
To see the digital counter display unit in action, watch the following YouTube video:
This is an example of how the display unit was designed into a golf club bending machine, and used to display golf club loft and lie angles.
Two incremental encoders are used to measure the loft and lie angles that the machine is bending the golf clubs to. The encoders generate 2-channel A/B quadrature signals that get passed on to the display unit by way of two short cables that plug into the back of the display.
The encoders being used in this golf club bending machine application have a resolution of 360 CPR (cycles per revolution). Because of the quadrature nature of the signals coming from the encoders, the display is able to do X4 (times four) counting on the 360 cycles per revolution signals. This quadrupling of the resolution by the display unit results in 1,440 (360 times 4) counts per revolution, or 0.25 of a degree resolution.
You can see in the YouTube demonstration video, that the loft and lie angles are preset to zero by pressing the PRESET buttons on the front of the display after the locking pins are in place.
Other Display Specifications And How To Get Your Hands On One!
The display unit dimensions are 3.29 in. X 2.42 in. X 1.00 in.
The housings are made from a black flame retardant ABS plastic material that is rated UL94-5VA.
The 5V d.c. power available on pin 4 of the connectors on the back of the display unit can source up to 1 ampere of current total.
As was mentioned previously, the display units are adaptable to many applications and can be used with many kinds of encoders and sensors. You can contact the manufacturer with the details about your application, and they will factory program the display to meet your requirements.
For example, with the golf club bending machine application described in the previous section of this article, the customer specified all the requirements of the application before ordering the display units. It was specified that:
1. The display would need to work with 360 CPR encoders to get a resolution down to 0.25 of a degree using X4 (times four) counting on the quadrature.
2. The top four LED digits of the display unit would be used to display loft angle readings in the range of +/-90.00 degrees. The bottom four LED digits would be used to display lie angle readings also in the range of +/-90.00 degrees.
3. The color of the top four LED digits and the bottom four LED digits would be green.
4. Both the top and bottom displays would reset to zero (0.00) when their respective “PRESET” buttons were pressed.
To learn more or to get your hands on one or more of these great display units from CNL Devices Inc., send your email inquiry to firstname.lastname@example.org.
If you have found this article helpful, or if you have any questions or suggestions, please use the comments section below to give me your feedback.