PVCuni/PVCduo Ion Gauge and Vacuum System Controller

We are pleased to announce that the PVC range of instruments will be under the management of Thyracont Vacuum Instruments GmbH (www.thyracont.de) from January 2021.

For all enquiries, please contact: direct@thyracont-vacuum.com

EpiMax would like to take the opportunity of thanking all our loyal customers for their help and support over many years; we feel confident that the PVC range has a bright future with Thyracont.








PVCuni and PVCduo Summary:

  • 1U 19" rack unit.
  • PVCuni: 1x UHV ion gauge + thermocouple (bake-out) + 1x Pirani (EMP521 or EMP841)
  • PVCduo: 2x UHV ion gauge + thermocouple (bake-out)
  • 2x module slots to add Pirani (EMP521 or EMP841), intelligent gauge, second thermocouple...
  • Auto-ranging emission, or 11 manual emission settings
  • Ramped power degas
  • Pressure measurement during degas
  • RIPPA - rapid response to pressure bursts
  • Precision, stable electrometer
  • Gauge head lifetime indication
  • User-definable Interlock Hub provided via 7 output trips and 4 digital inputs
  • 2x 0-10V analogue outputs. Each AO can be user-assigned (e.g. ion/secondary gauge pressure/emission, temperature...) and the pressure vs voltage range set.
  • Integrated, interlocked, multi-step bake-out controller. Dual zone option
  • 2x module slots for addition of optional secondary gauge support (e.g. Pirani, smart gauge....). Range of modules available
  • Auto pump-down
  • 2x user-definable on/off single or cyclical Timers (e.g. for pump regeneration, TSP firing...)
  • Simple to use manual interface
  • Full computer control using binary MODBUS and ASCII-based QueBUS protocols. Both offer multi-parameter read/writes in the same message
  • Multi-drop RS232/RS485 interfaces as standard with easy daisy-chaining
  • Full compatibility with VacTools
  • Supported by our range of Accessories and Gauge heads


  • All HV and UHV system pressure and interlock monitoring, and process control
  • UHV system bake-out management
  • Automated UHV system management
  • MBE beam flux monitoring
Process & Vacuum Controller (PVC) Overview

Following over 20 years experience in vacuum measurement and system control, and building on its predecessors (the PVCi and PVCX), the PVCuni and PVCduo provide our most powerful, yet easy to use controller to date.
PVCs integrate several vacuum system functions into a single 1U high unit, including UHV measurement from 1 or 2 ion gauge heads, support for up to 2 secondary gauges, thermocouple input for multi-step bake-out control, and a flexible user-configurable interlock hub to provide system protection and bake-out power switching. Integrating these functions simplifies vacuum system management, reducing wiring and frees up valuable rack space.
Comprehensive, fast communications are standard, and our freeware VacTools app  provides  data logging, graphical data presentation and much more, including real-time data linking to your software.

PVC Ion Gauge Support

  • Dual-filament Iridium-based ion gauge heads (Thoria- or Yttria-coated)
  • High stability µprocessor PID-controlled emission. Measured with the ion current for accurate pressure conversion
  • Smooth dc current driven filament power supply for low noise, high stability and vibration-free operation
  • Measurement displayed in pressure units (mB, T or P). Alternatively displayed as direct ion current (emission corrected) for BFM applications to 4 significant figures (auto-ranging pA, nA, µA, mA )
  • Emission current can be set to a fixed value in the range 0.05 to 10mA...
  • Alternatively, Auto-emission automatically optimizes the emission for the pressure of operation and protects the gauge head from pressure bursts
  • Smooth "bumpless" transition to and from gauge Degas mode
  • Gauge remains protected as pressure measurement is maintained during Degas
  • A secondary gauge can be linked with the ion gauge so that they operate as a single unit

Secondary Gauge Support
  • Built-in support for one EMP521 or EMP841 Pirani gauge head
  • A module slot allows the user to add support for an additional gauge
  •  A module slot permits addition of support for another secondary gauge
  • Secondary gauges can optionally be "linked" with ion gauge operation for them to operate seamlessly as a singe gauge. This allows the single "dual-gauge" pressure to be displayed as a single device, as well as automatically turning the ion gauge  on/off at user-specified pressures.
Thermocouple, Multi-Step Bake-out Control
The PVCs support multi-step ramp/soak vacuum system bake-out control:
  • Supports input from a type K thermocouple - for example, see PVC Accessories
  • Any combination of Interlock Hub trips can be assigned for power switching
  • Up to 6 ramp/soak steps with 99.9 hours per step
  • Full interlock support. User-define gauge pressure and digital input to delay, suspend or terminate bake-out
  • Auto-degas of ion gauge at end of the bake-out
  • Optional dual zone bake-out (requires "K" module installed in slot).
Expansion Modules
The PVC provides two module slot to add additional vacuum or temperature measurement. The modules can be installed by the user and they are auto-detected.

The currently available modules:
  • "W" module (supersedes the "U" module). The "W" Universal Input module interfaces with any device that outputs a voltage, converting this to a pressure that can be used displayed by the PVC and also used as part of the user-defined interlock hub. Devices include: other gauge controllers with analogue outputs, intelligent controllers (linearized Piranis, Convectron, Stinger and many more), 
    The input voltage range, corresponding pressure range and lin/log relationship is user definable. The module can also power the device, providing option for 15V or 20V output at up to 100mA - adequate for many devices - and the power to the device can be switched on and off by the user. Optional up-scaling protects against disconnection.
  • "E" module. Supports an additional EMPir521 Pirani gauge head
  • "F" module. Supports an additional EMPir841 Pirani gauge head
  • "V" module. Supports (now obsolete) VacGen Pirani gauge heads.
Interlock Hub

A key function of the PVC is to act as an "Interlock Hub" to provide protection to the gauge and your system. The Interlock Hub is completely user-configurable, often removing the need for external sensor/switch units and reducing the amount of hard wiring required.

The Interlock Hub links together the ion gauge performance, the secondary gauge measurements, digital output trips, digital inputs, analogue outputs and bake-out in a simple to define user-configurable matrix:

  • PVCs provide 7x trips (4 change-over relay, 3 opto-isolated open collector). Each trips can be independently configured to respond to any gauge pressure or operating mode, switch bake-out heaters or be triggered over communications.
  • PVCs provide 4x opto-isolated digital inputs that can respond to external events. They can be configured to control ion gauge operation (emission or degas on/off, trip the gauge, suspend degas) or suspend/abort bake-out.
  • As well as for data logging, the analogue outputs can also be used to interact with the interlocks
Communcations, VacTools and vtde
  • RS232 and RS485-based communications. Up to 8 controllers per RS232 port and 32 per RS485 (pc port dependent)
  • 2 parallel connectors for ease of daisy chaining
  • MODBUS binary protocol. 32-bit floating-point data transfer. Up to 16 parameters read and 16 parameter write per message loop
  • QueBUS ASCII-based protocol. Up to 16 parameter read/write per message loop
  • Free VacTools software for multiple PVC control/monitoring
  • Add PVC comms to your own software with minimum programming  using vtde
PVCuni and PVCduo
Ion Gauge:
PVCuni: 1x Dual filament UHV. Thoria- or Yttria-coated Iridium filaments
PVCduo: 2x Dual filament UHV. Thoria- or Yttria-coated Iridium filaments (simultaneous operation of both gauges)
Filament Drive:
Constant current dc (4A/9V)
µprocessor controlled precision PID control
Manual Emission:
User selections: 0.06, 0.1, 0.15, 0.25, 0.4, 0.6, 1, 1.5, 2.5, 4, 6, 10mA
Emission automatically adjusts for optimum performance at the measured pressure
Emission features:
Soft-start. Optional "new filament" setting to permit gentle heating.
User-definable min & max emission
Ramped low/mid/high power
Degas Features:
User-defined ramp/soak periods. User-defined pressure suspend to allow vacuum recovery.
Degas Pressure:
Continuous measurement during degas
Degas on/off:
No interruption to pressure measurement during degas start/stop
Effective Range: 0.1pA to 1mA; equates to 1x10-13 to 1 mBar (gauge dependent)
High thermal stability, low drift
1.0 to 99.9 (resolution 0.1)
User-defined auto pump-down: backing gauge dependent ion gauge start-up pressure; trip allocation for external events (valves...), delay time, restart time etc...
Built in:
Supports VSP521 or VSP841. User calibration available.
Number of Modules:
Tertiary Gauge Module Options:
"V": VG Pirani
"E": VSP521
"F": VSP841
"W": Universal for output from other gauge controllers or active gauge heads such as cold-cathode gauges (e.g. PKR251/261, IKR270), mini-convectron, Stinger, microPirani...). Note: some of the gauges can draw their power from this module (max 100mA@14.5V).
Built in:
Type K thermocouple. Standard mini-thermocouple connector
Room temperature to 900°C (16 bit resolution).
Precision CJC.
Reproducibility <±0.2°C. Absolute <±2°C. User calibration available.
Bake-out Functions:
6x ramp/soak steps, each up to 99.9 hours duration.
Individual trip allocation for power switching (e.g. 3 trips for 3Φ).
User-defined pressure interlocking (ramp suspend/time suspend/abort).
User-defined temperature hysteresis.
Optional auto-degas at end of bake-out.
7 (4x SPCO relays 1A24Vdc/ 0.5A125Vac + 3x NPN open collector 100mA/12Vdc)
Trip assignments:
Individually assignable: external interlock to any ion or backing gauge, ion gauge status (on, off, degas), bake-out power switching, pump down external drive...
Digital Inputs:
4x opto-isolated inputs. 3-30Vdc; 2.4kΩ input resistance.
Digital Input assignment:
External interlock as trip for ion gauge; control over ion gauge on/off and degas either via input state or toggle state, bake-out trip, pump-down trip, backing gauge operation...
Interlock Response times:
0.2 sec max.
Typically <0.1sec
2x Outputs:
Full scale range: 0V to 10.2V (12 bit resolution).
User-definable min and max voltage and related pressure value
Precision reference-based: <±0.2%.
Ion gauge (emission and sensitivity corrected), any secondary gauge, gauge combinations, bake-out temperature...
User-defined voltage range vs. assigned pressure/temperature range.
Linear or logarithmic relationship...
19" rack mounting: WxHxD: 484x44x260mm
115/230Vac. Live and Neutral fused: 2A for 230Vac, 3.15A for 115V
Power Consumption:
 4W (ion gauge off); max: 40W (high degas); typical: 4-10W (ion gauge on).
Single gold OLED display. Graphical 200x16 pixel resolution
Data Resolution:
Ion gauge:
Pressure: 1 or 2 decimal place resolution; Current: 4 significant digits (mA/µA/nA/pA)
Secondary/Tertiary gauges: 1 decimal place resolution.
Temperature: <0.05°C measurement resolution, 0.1°C display resolution.
Manual input:
Intuitive menu-driven via 5 front panel touch buttons
Comms ports:
Multi-drop RS232 (up to 8 units (port dependent)) and RS485-3 wire (up to 16 units).
[Mid-2014: TCP/IP option]
Comms Settings:
4800, 9600, 19200, 38400, 57600 baud.
Parity: None, Odd or Even. 8 bit + 1 start + 1 stop
Comms Protocols:
MODBUS RTU protocol. Multiple parameter read/write; floating point resolution.
QueBUS protocol: ASCII-based with multi-parameter read/write messaging.
Comms connection:
2x RJ45 for simple daisy-chaining

Dimensions of all PVC models. Please add 50mm for rear panel earth stud and connectors