5.3.1 DigiLine
The active gauges in the DigiLine range provide their pressure signals via a serial RS-485 or fieldbus interface. They are supplied with 24 VDC. The various application options are described in Figure 5.9.
Figure 5.9: Application concepts DigiLine
Up to two gauges can be operated and their pressure values displayed with the DPG 202 power supply unit. The DPG 202 has a USB interface for connecting a PC. Signals from the active DigiLine vacuum gauges can also be directly processed by a PLC or PC and displayed by the DokuStar Plus software.
Optional versions of DigiLine gauges are available with interfaces for Profibus-DP and DeviceNet fieldbus standards. This enables these vacuum gauges to be easily integrated into the fieldbus networks of plant control systems with all the known advantages of savings through less wiring and cabling and fast initial start-up.
A further option is DigiLine gauges with an additional analog output and switch-points. The analog output can be used for tasks such as setting up a local pressure isplay for a transmitter that is linked to a central control system. The switch-points allow hard-wired safety functions to be provided independently of the controlling computer.
Active DigiLine vacuum gauge offer the following advantages:
- The pressure range from 5 · 10-10 to 2,000 hPa covers the entire vacuum range
- Freely combinable components
- Secure data transmission thanks to digital signals
- Pressure values are transmitted numerically so no curve correction or conversion is required
- Profibus-DP and DeviceNet fieldbus interfaces
- Data can be analyzed directly on a PC with DokuStar Plus software
- Remote control for easy adjustment
- Protection class IP54 and DIN M12 connector assemblies for reliable operation in harsh environments
Active DigiLine single-sensor gauges are available in the form of a piezo-diaphragm system CPT 200 (2,000 – 1 hPa) and a Pirani system PPT 200 (1,000-10-4 hPa).
The following gauges with combination sensors are available in the DigiLine series:
- Piezo-Pirani combination RPT 200. Since the thermal conductivity effect for the Pirani vacuum gauge for pressures p > hPa is not a function of pressure, a diaphragm vacuum gauge is used for pressures p > 10 hPa. This affords good accuracy throughout the entire measurement range from 1,200 to 1 · 10-4 hPa, enabling processes such as chamber venting to be precisely controlled by this gauge.
- Pirani-cold cathode combination MPT 200. This combination covers the pressure range from 1,000 to 5 · 10-9 hPa. The gas discharge of the cold cathode measuring sensor is initiated by the pressure that is measured with the Pirani sensor. Using this process prevents inadvertent activation of the cold cathode at excessive pressure, thus avoiding contami- nation.
- Pirani/Bayard-Alpert combination HPT 200. This covers a pressure range from 1,000 to 5 · 10-10 hPa. Pressure monitoring by the Pirani sensor protects the hot cathode gauges from operating at excessively high temperatures and prevents burn-out of the hot cathode. This enables extremely long cathode service life to be achieved.
