He Recondensing Controller

The "He recondenser" contoller is designed from industrial components and allows to condense as much helium as possible while maintaining the pressure just above the atmospheric pressure in the liquid helium bath of a cryostat or cryomagnet. The pressure in the liquid helium bath is measured relative to the atmosphere pressure with a relative sensors from GE or other companies. The heating power delivered inside the liquid helium bath or to the second stage of the cooler is easily managed with a process controller (Eurotherm model 3504).

Intuitive interface

The unit measures and displays permanently the liquid helium bath pressure with a vertical bar graph and large digits in hPa which are visible quite far away from the cabinet. The output heating power is displayed with a horizontal bar graph in % and a number in mW.

The user can changed the helium bath relative pressure setpoint at anytime and the controller adapts the output heating power automatically. Alarms are set using high and low levels and the unit applies PID parameters to regulate the pressure. In order to display the right heating power delivered to the bath, the user can enter a lead wire compensation in Ohms.

If needed, it is also possible to control manually the ouput heating power in mW.

Easy settings

The He recondenser is calibrated in a very few steps:

  • prepare the cryostat with liquid helium
  • enter the Settings mode
  • check the high and low level values
  • set the lead wire compensation value
  • quit the Settings mode
  • enter a pressure setpoint, e.g. 10 hPa

The PID parameters can also easily be modified from the Settings menus according to the user wishes.

Full remote control

Computer control via RS-485 and Ethernet is available. All parameters can be read and set, even the lead wire compensation. The communications are based on the Modbus communications protocol which has become a de facto standard in industry. We provide a Modbus XOP and a Procedure for controlling the level monitor with Igor Pro.

The ILL He recondenser controller has been carefully designed and manufactured to provide hours of trouble free service. Its user interface has also been designed so as to simplify as much as possible its operation. The controller also has several features that are not available on other commercial systems: a large display for easy reading on large instruments and a full remote access allowing users to control different cryostats without the need for recalibrating.

The controller is delivered fully tested and ready to be calibrated. We describe below how to install, operate and remotely control this device.


The user enters the pressure set point and the controller changes the cold-valve position automatically until the pressure is stabilized. When working in manual mode, the user controls directly the pressure applied to the piston of the cold-valve and reads continuously the helium pressure.


The controller can be remotely controlled through a RS485 or Ethernet link using the Modbus communication protocol (public function code 3).

The ILL cold-valve controller is presently delivered with the version 1.05 of the soft-wired program installed and preset with Orange cryostats parameters. Remote control is performed using the registers listed below.

Firmware Update

The latest release 1.02 provides enhanced pages and a safer behaviour at startup.

Size and Weight

The monitor fits within a 19"/3U chassis.

  • Height: 129 mm (5.1 inches)
  • Width: 143 mm (5.6 inches)
  • Depth: 355 mm (14 inches)
  • Weight: 2.70 kg (5.95 pounds)

Modbus registers

He pressure value in hPa-9999991
He pressure set point in hPa01005
Heating power in mW09994963
Low level alarm in hPa-1001004969
High level alarm in hPa-1001004966
Output in %01004
PID - Proportional0999996
PID - Integral0999998
PID - Derivative0999999
Firmware version1104977

Electrical and operating requirements

Contact us if you need a 100V AC / 60 Hz unit.

  • Line voltage: 240V AC
  • Frequency: 50Hz
  • Operating temperature: 10 to 35°C (50 to 95 °F)
  • Storage temperature: -24 to 45°C (-13 to 113 °F)
  • Relative humidity: 5 to 85% noncondensing

Please find below the release history and some instructions for updating the firmware. To get the most recent release of the firmware, please contact us

Release History

  • 1.00 - Initial release
  • 1.01 - Added lead wire compensation
  • 1.02 - Improved pages and safety at startup

Instructions for updating the controller

  • Install iTools (available here),
  • Connect the controller to the computer with an Ethernet cable,
  • Configure the TCP/IP parameters of the computer:
    • Select the Connection panel and click on TCP/IP Properties,
    • Enter the fixed IP address ( for NOMAD),
    • Enter the subnet mask,
    • Enter the gateway address,
  • Launch iTools and open the OPC Server window,
  • Open the "Scan for TCP hosts..." panel from the Add/New TCP Network Port menu command,
  • Enter the TCP/IP address (standard address of the He recondensing controller),
  • Launch the scan and stop it once the controller detected,
  • Reduce the OPC Server window (do not close it!),
  • Click on the Scan icon of the main iTools toolbar and launch a search for connected instruments,
  • After the scan, click on the Load icon of the main toolbar, select the new firmware and launch the update.