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