This post is part of the Rack box project series.
RS-232 interface module, with voltage measurement. Used to communicate with the emergency power off unit in the Rack box project. Installed inside Rack box status panel. Uses an AVR ATmega8 microcontroller.
Table of contents
With this interface it’s possible to trigger and reset the emergency power off 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 power off is triggered and gives the option of disabling the emergency strobe.
It has three LEDs and one two-way switch on the Rack box 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.
- Value from emergency supply 12V
- Emergency shutdown status
- Status on switch 1
- Status on switch 2
- Trigger emergency shutdown (1 sec pulse)
- Reset emergency shutdown (10 sec pulse)
- Deactivate strobe (on/off)
- LED 1
- 0: Off
- 1: Green
- 2: Red
- LED 2
- 0: Off
- 1: Green
- 2: Red
- PC0 - Emergency supply 12V voltage for volt meter
- PC1 - Emergency shutdown active (Emergency power off unit)
- PC2 - Switch 1
- PC3 - Switch 2
(ADC × 5) × 0.006 ≈ V ± 0.03
- PB0 - Trigger emergency shutdown (Emergency power off unit)
- PB1 - Reset emergency shutdown (Emergency power off unit)
- PB2 - Deactivate strobe
- PB3 - LED 1 Green
- PB4 - LED 1 Red
- PB5 - LED 2 Green
- PD6 - LED 2 Red
- PD7 - Activity LED
- PD5 - Life-signal (to Module stability monitoring unit 2) (opto-isolator)
See Rack box status panel for D-Sub connector.
Interfacing is done with RS-232, using MAX232 or MAX202 and the SIOS protocol.
- Baud: 9600
- Data bits: 8
- Parity: None
- Stop bits: 1
- Bascom-AVR source is available in a git repository:
- 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
Last commit 2023-02-05, with message: Add series for the rack box project.