Tuesday, March 29, 2011

Analog - Digital With Matlab

For a better understanding of how to specify device settings when using both analog and digital signals, this section uses the I/O board DAS-1601 from Keithley-Metrabyte as an example. The following is a specification summary of the DAS-1601 board:

  •  Analog input (A/D) -- 16 single-ended or 8 differential analog inputs (12-bit), polarity is switch configured as either unipolar (0 to 10 volts) or bipolar(+/- 10 volts). Gain is software configured to 1, 10, 100, and 500. 
  • Digital input -- Four unidirectional digital inputs Analog output (D/A) -- Two
  •  analog outputs (12-bit). Gain is switch configured as 0 to 5 volts, 0 to 10 volts, +/- 5 volts, or +/- 10 volts 
  • Digital output -- Four unidirectional digital outputs 
  • Base address -- Switch configured base address 
This section explores different configurations for input signals. Once an Analog Input block has been placed in the model and the I/O board selected and configured, you can set up the Analog Input block to handle input signals. Single analog input -- The most basic case is for a single analog input signal that will be physically connected to the first analog input channel on the board. In the Block Parameter: Analog Input dialog box, and the Input channels box, enter 1 or [1]

The use of brackets is optional for a single input. Input vector with differential analog -- Analog channels are numbered starting with channel 1 and continue until you reach a number corresponding to the maximum number of analog signals supported by the I/O board. In the case of the DAS-1601, when configured as differential inputs, eight analog channels are supported. The analog input lines are numbered 1 through 8. The complete input vector is

[1 2 3 4 5 6 7 8] or [1:8]

If you wanted to use the first four differential analog channels, enter
 [1 2 3 4]
Input vector with single-ended analog -- Now, assume your DAS-1601 board is configured to be single-ended analog input. In this case, 16 analog input channels are supported. The complete input vector is
 [1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16] or [1:16]
To use the first four single-ended analog input channels, enter
 [1 2 3 4] or [1:4]


Monday, March 28, 2011

IR232 Infrared to RS-232 Converter

The Industrologic IR232 is an infrared to RS-232 converter that is based on the 12 bit Sony SIRCS protocol. In addition to being able to send and receive control codes to and from the infrared and RS-232 ports, it can also be configured to send specific character strings to the serial port when selected infrared codes are received. This will allow it to act as a host and controlling device to any slave device that can accept RS-232 commands.

On-board 40 KHZ infrared receiver module and 940nM high-power infrared LED Visible LED to confirm reception of infrared transmissions
EEPROM for storage of configuration information and character strings Multiple modes of operation available-
- Send programmed messages when specified infrared codes are received
- One and two byte binary transmission and reception
Serial port with true RS-232 interface and DB9F connector matching PC compatibles
Selectable baud rates up to 19200 baud
Pin-type power jack for easy connection to wall block power supply
On-board +5 volt power supply with +5 volt output available on DB9 for auxiliary devices
Includes all items needed for immediate use: Wall block power supply, RS-232 cable for connection to PC compatibles during setup, and terminal emulation software for PC compatibles.


Tuesday, March 8, 2011

Simple Switch On Time Delay Circuit

This Switch On Time Delay circuit has been designed to create a lamp switch operated electronically with an option of setting a delay in the time of execution of operation to reduce one or more lamps in a stairwell or any other places where this circuit may be useful. The circuit can be useful to control various lamp or appliances that can be connected in relay contacts.

The circuit that takes advantage of the emitter/base breakdown voltage of an ordinary bi-polar transistor. The reverse connected emitter/base junction of a 2N3904 transistor is used as an 8 volt zener diode which creates a higher turn-on voltage for the Darlington connected transistor pair. Most any bi-polar transistor may be used, but the zener voltage will vary from about 6 to 9 volts depending on the particular transistor used. Time delay is roughly 7 seconds using a 47K resistor and 100uF capacitor and can be reduced by reducing the R or C values. Longer delays can be obtained with a larger capacitor, the timing resistor probably shouldn't be increased past 47K. This Switch On Time Delay circuit should work with most any 12 volt DC relay that has a coil resistance of 75 ohms or more. The 10K resistor connected across the supply provides a discharge path for the capacitor when power is turned off and is not needed if the power supply already has a bleeder resistor.