Serial interface module for emergency power off

From CaveLab
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This module was part of the rack box project — which was terminated when I moved out of my first apartment.
DEIM installed in the Rack status panel

With DEIM it's possible to trigger and reset the emergency shutdown from Serial Client, the voltage on the 12V emergency supply is also measured and shown in Serial Client. The module also registers if the emergency shutdown is triggered and gives the option of disabling the emergency strobe. DEIM has three LEDs and one two way switch on the Rack status panel, a yellow LED flashes when there is serial activity. Two LEDs are dual colored (green/red), the color can be controlled from the computer. The switch can be set up using triggers in Serial Server.

Commands

  • Inputs
    1. Value from emergency supply 12V
    2. Emergency shutdown status
    3. Status on switch 1
    4. Status on switch 2
  • Outputs
    1. Trigger emergency shutdown (1 sec auto off)
    2. Reset emergency shutdown (10 sec auto off)
    3. Deactivate strobe (on/off)
    4. LED 1
      • 0 Off
      • 1 Green
      • 2 Red
    5. LED 2
      • 0 Off
      • 1 Green
      • 2 Red

I/O

Inputs

  1. PC0 - Emergency supply 12V voltage for volt meter
  2. PC1 - Emergency shutdown active (Emergency shutdown unit)
  3. PC2 - Switch 1
  4. PC3 - Switch 2

Calculations

Voltage

Outputs

  1. PB0 - Trigger emergency shutdown (Emergency shutdown unit)
  2. PB1 - Reset emergency shutdown (Emergency shutdown unit)
  3. PB2 - Deactivate strobe
  4. PB3 - LED 1 Green
  5. PB4 - LED 1 Red
  6. PB5 - LED 2 Green
  7. PD6 - LED 2 Red
  8. PD7 - Activity LED
  9. PD5 - Lifesignal (to Module stability monitoring unit 2) (optoisolator)

D-Sub connector

See Rack status panel for D-Sub connector.

Communication

Interfacing is done with RS-232, using MAX232 or MAX202.

Serial settings

Baud
9600
Data bits
8
Parity
None
Stop bits
1
Start command
*
Module ID
004

Source code

Git-alt-brands.svg
Bascom-AVR source is available in a git repository:
https://github.com/thomasjsn/AVR-Emergency-serial-interface-module

Gallery

Schematic drawing

Deim circuit.png

Parts list

Qty. Part
1 × AVR ATmega8-16PU, DIL-28, 16 MHz, 23 I/Os
5 × Capacitor, aluminium electrolytic, 1 µF, 50V
1 × Capacitor, aluminium electrolytic, 10 µF, 25V
2 × Capacitor, aluminium electrolytic, 47 µF, 25V
2 × Capacitor, ceramic, 1 nF, 100V
2 × Capacitor, metallized polyester foil, 10 nF, (0.01 µF)
1 × DIL socket, 16-pin, 7.62mm
1 × DIL socket, 28-pin, 7.62mm
1 × DIL socket, 6-pin, 7.62mm
1 × Diode, small signal, 1N4148/Ph
1 × Heat conducting film for heatsink, Adhesive, TO220
1 × Heatsink, 15K/W @ 4W, 28mm 7g, TO220
1 × Optocoupler, single, CNY17F-3, DIL-6
32 cm2 PCB, stripboard, 100x160mm, 160cm2
4 × Resistor, carbon film, 0.25W, 330 Ω, 5%
4 × Resistor, carbon film, 0.25W, 4.7 kΩ, 5%
3 × Resistor, carbon film, 0.25W, 10 kΩ, 5%
1 × Resistor, carbon film, 0.25W, 100 kΩ, 5%
1 × Resistor, metal film, 0.6W, 20 kΩ, 1%
1 × RS232 interface, MAX232CPE, dual
1 × Spacer, round unthreaded, 3mm, Ø6mm, Delrin
17 × Straight pin header, female, Single row, 2.54mm
24 × Straight pin header, male, Single row, 2.54mm
3 × Transistor, NPN, 100 mA, 45V, 0.5W, BC547B
1 × Voltage regulator +5V, 1 A, 7805PI