M21(Rev. 1.1) User Manual Revision: 31/08/2009 http://cnc4pc.com/TechDocs/M21R1_1_User_Manual.pdf 1/12 M21- 12ODI EXPANSION BOARD Rev. 1 User manual Rev. 2 1. Overview This expansion board provides 12 discrete optoisolated inputs for +5vdc TTL signals. 2. Features • 12 Optoisolated Discrete inputs • PULL-UP or PULL-DOWN selection for inputs. Includes jumpers to select the best input configuration for your application. • Buffered inputs. • Input pins with close by ground or +5vdc connections. • Screw-On terminals. • Fully optoisolated. • Support for up to 10 KHz optoisolation.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Calculating the R1 value. Note: Being an unknown value resistor, in the follow explanation this resistor go to be
named Rx.
RX = VEX.(R/V) - R (1)
Where:
VEX is the external power supply voltage
V is the voltage across the R resistor
To calculate the internal resistor (Rx) values are required an external resistor and a voltmeter. Do the connection as are shown in the figure above and do the calculations using the equation (1).
Note. The user should know the R value to do this operation. It is recommended a 4.7KOhm@1/2W.
For example, if you are using a 12V power supply (VEX), and use an 4.7KOhm as external resistor (R), and the voltage across R is 6V, using the equation 1, the Rx value is 4.7KOhm.
Disclaimer: Use caution. CNC machines could be dangerous machines. DUNCAN USA, LLC or Arturo Duncan are not liable for any accidents resulting from the improper use of these devices. The M21 is not fail-safe device, and it should not be used in life support systems or in other devices where its failure or possible erratic operation could cause property damage, bodily injury or loss of life.