Langmuir Trough

This Langmuir trough is controlled with a Process Logic Controller M251 from Schneider. This PLC reads the analog signal returned by the surface tensiometer and drives the barriers through a Kibron electronics. The temperature of the liquid interface is controlled with a thermostatic bath and monitored with a compact pyrometer. A gas can be circulated above the interface via a flow-rate controller. In addition, the PLC controls the heating of the neutron and laser windows to prevent condensation. All these devices are controlled from the touch panel of the PLC which is also used to control the Adsorption Troughs.

Barriers are controlled manually with a touch panel or remotely with NOMAD. Their calibration is manual or semi-automatic and must be performed from the interface before closing the casemate. During neutron data acquisition, two modes of operation are proposed: area controlled and pressure controlled. In the pressure controlled mode, the movements of the barriers are determined by the Kibron electronics to maintain the wanted pressure (static or dynamic).

40001ReadRealSurface tension signal x (V)
40003ReadRealCoefficient a
40005ReadRealOffset due to paper probe b
40007ReadRealConstant for zeroing the sensor (relative measurement)
40009ReadRealSurface tension a x + b - c (mN/m)
40081ReadRealTemperature setpoint (°C)
40083ReadRealTemperature (°C)
40087ReadRealGas flow rate (l/min)
40089ReadRealGas flow rate setpoint (l/min)
40119Read/WriteRealNOMAD Control — Temperature setpoint (°C)
40121Read/WriteRealNOMAD Control — Gas flow rate setpoint (l/min)
40125Read/WriteRealNOMAD Control — Temperature tolerance (°C)
40127Read/WriteRealNOMAD Control — Gas flow rate tolerance (l/min)
40129Read/WriteIntegerNOMAD Control — Year
40130Read/WriteIntegerNOMAD Control — Month
40131Read/WriteIntegerNOMAD Control — Date
40132Read/WriteIntegerNOMAD Control — Hour
40133Read/WriteIntegerNOMAD Control — Minute
40134Read/WriteIntegerNOMAD Control — Second
40201ReadBoolean (bit 0)Temperature alarm (yellow: out of tolerance)
 ReadBoolean (bit 2)Temperature default (red)
 ReadBoolean (bit 3)Gas flow rate alarm (yellow: out of tolerance)
 ReadBoolean (bit 5)Gas flow rate default (red: out of gas)
 ReadBoolean (bit 7)Condensation default (red: lid unplugged)
40202ReadBoolean (bit 0)NOMAD Control — Thermostatic bath default (red: no communication)
 ReadBoolean (bit 1)NOMAD Control — Idle
 ReadBoolean (bit 2)NOMAD Control — Running
 ReadBoolean (bit 3)NOMAD Control — Local (0) / Remote (1)
 Read/WriteBoolean (bit 4)NOMAD Control — Default acknowledgment
 Read/WriteBoolean (bit 5)NOMAD Control — For resetting the PLC clock
40251ReadRealVoltage (mV) - Signal recieved by the KIBRON controller
40257ReadRealArea (mm2)
40277ReadRealBarriers Speed (mm/min)
40361WriteRealManual Mode: Barriers Speed Setpoint (mm/min)
40351Read/WriteBoolean (bit 0)Manual mode: Compress
40352Read/WriteBoolean (bit 0)Manual mode: Relax
40353Read/WriteBoolean (bit 0)Manual mode: Stop
40367Read/WriteRealArea Controlled: Delay (min)
40373Read/WriteIntegerArea Controlled: Number of Loops
40363Read/WriteRealArea Controlled: Barriers Speed Setpoint (mm/min)
40372Read/WriteRealArea Controlled: Target Area (mm2)
40354Read/WriteBoolean (bit 0)Area Controlled: Start (1)/Stop (0)
40371Read/WriteRealPressure Controlled: Delay (min)
40375Read/WriteIntegerPressure Controlled: Number of Loops
40365Read/WriteRealPressure Controlled: Barriers Speed Setpoint (mm/min)
40369Read/WriteRealPressure Controlled: Target Surface Tension (mN/m)
40355Read/WriteBoolean (bit 0)Pressure Controlled: Start (1)/Stop (0)