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Operation

  1. If on, turn off NIM crate to disable interlock (otherwise chiller won't start)
  2. Turn on SVT power supply crate (turn key to "local on"), make sure red "interlock" light comes on (i.e. tripped)
  3. Set flow manifold valves
  4. Start chiller (power button on front panel)
  5. Turn on NIM crate, make sure Arduino's green "ON" light and flow switch's red "flow above threshold" light turn on, SVT power supply's red interlock light turns off
  6. Do stuff to start power and DAQ

Systems

Power

CAEN SY1527

Serial console

Serial port is connected to Windows desktop; run HyperTerminal (Start/Prorams/Accessories/Communication/HyperTerminal) and open the "CAEN SY1527" shortcut (set to COM1, 9600 baud, hardware flow control).

Cooling

Chiller

Polyscience 6506T

Max outlet pressure set to 40 psig using internal pressure bypass

Interlock board

Arduino Leonardo (http://arduino.cc/en/Main/ArduinoBoardLeonardo)

Source code: serial.ino (serial_hps_svt.ino)

Need micro-USB cable to reprogram. Software is already installed on Windows laptop.

Inputs:

  • HTM2500LF temperature+humidity sensor inside Lexan box
  • Flow switch in cooling system return line
  • RS-232 connection to chiller - status, set T, measured pressure/flow/T

Thresholds:

  • Ambient T inside SVT Lexan box < 25 C (set in Arduino script)
  • Ambient RH inside SVT Lexan box < 5 % (set in Arduino script)
  • Cooling system flow > 20 GPH (adjustment screw on flow switch)

Logic:

  • Check inputs every 1 s; if any input is abnormal, trip and stay tripped (must reset Arduino board to clear)

Outputs:

  • RS-232 to chiller: if tripped, send "stop" command every 1 s
  • Interlock to CAEN crate (5V normal, 0V tripped) - trip turns off all outputs immediately
  • Prints inputs to USB serial connection every second (if plugged in)
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