Honeywell VCR DCP200 Manuel D’Utilisation

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DCP200 Profile Controller & Recorder - Product Manual
Page 164
Glossary
51-52-25-150, Issue 1 – April 2009
Triac
A small internal solid state relay, which can be used in place of a mechanical relay in 
applications switching low power AC, up to 1 amp. Like a relay, the output is time 
proportioned, but much faster switching cycle times are also possible, leading to superior 
control. As a solid-state device, a Triac does not suffer from contact degradation when 
switching electrical currents. A snubber should be fitted across inductive loads to ensure 
reliable switch off the Triac. A triac cannot be used to switch DC power.
USB Menu
If the USB option is fitted, the USB Menu can be accessed from the Main Menu. This menu 
is lock code protected.
The USB Menu allows the user to read or write files to a USB memory stick. The current 
configuration of the instrument can be downloaded to the stick or the instrument can be 
completely reconfigured using a pre-stored file that has been downloaded earlier, created 
using the PC software, or even taken from another instrument.
If the Data Recorder option is present, the recordings can be downloaded to the stick for 
transport to the users PC for analysis. If the Profiler option is present, profiles can be 
downloaded to the stick or upload to the instrument using a pre-stored file that was 
downloaded earlier, created using the PC software, or even taken from another instrument.
Refer to the USB Menu information in the Configuration & Use section.
Valve Motor Drive Control (VMD)
This instrument can only control modulating valves that have a valve positioning circuitry that 
adjusts the valve position according to the level a DC linear mA or voltage output signal. 
Such valves normally require PI control instead of full PID.
Motorised modulating valves that do not have this type of circuit require special Valve Motor 
Drive controllers which have a “Three Point Stepping” control algorithm.
Solenoid valves can also be controlled using the standard PID algorithm as they behave in a 
similar way to relays, having just two states, open or closed.
VDC
This stands for Volts DC. It is used in reference to the linear DC Voltage input ranges. 
Typically, these will be 0 to 5V, 1 to 5V, 0 to 10V or 2 to 10VDC. Linear outputs can also 
provide DC voltages.
VMD
   - Refer to Valve Motor Control.