Interface Settings; 4-20Ma Interface; Full Scale Deflection - Dräger Polytron 8000 Series Technical Manual

Interface settings

13 Interface settings
For further information regarding the configuration of other interfaces consult the
relevant documents.
Interface
PROFIBUS
Foundation
Modbus RTU
13.1

4-20mA interface

The current output of the instrument during normal operation is between
4 and 20 mA and is proportional to the detected gas concentration.
Polytron
The factory default settings are user adjustable for application specific
requirements. This follows the NAMUR recommendation NE43.
13.1.1

Full scale deflection

Polytron
Some sensors offer an adjustable full scale deflection to limit the measuring range
for the 4-20 mA interface.
The full scale deflection (FSD) sets an endpoint within the measuring range of the
sensor. If the gas concentration reaches this endpoint, the 4-20mA interface
transmits 20mA.
Example: Required range 0 to 500 ppm CO (e.g. part number 6809605 default 300
ppm, range min/max = 50/1000 ppm).Select full scale deflection as 500 ppm. The
analog output will be linear between 4 mA = 0 ppm and 20 mA = 500 ppm.
Full scale deflection
The full scale deflection only sets the 20 mA endpoint of the analog interface for a
certain gas concentration. This has no effect on relays or on the display.
If the gas concentration exceeds the full scale deflection, the display continues to
indicate the measured value with the indicator "Measuring range of the analog
interface exceeded"
70
®
PA
TM
Fieldbus FF
®
8xx0 uses different current values to indicate various modes of operation.
®
8100 EC, 87x0 IR and 8200 CAT LC only
.
Technical Manual
Document
®
Technical PROFIBUS
9033782
Technical Fieldbus Handbook
9033783
Technical Modbus Handbook
9033781
|
Dräger Polytron
Handbook
®
8000 Series