70
Technical Manual
|
Dräger Polytron
®
8000 Series
Interface settings
13 Interface
settings
For further information regarding the configuration of other interfaces consult the
relevant documents.
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
®
8xx0 uses different current values to indicate various modes of operation.
The factory default settings are user adjustable for application specific
requirements. This follows the NAMUR recommendation NE43.
13.1.1 Full
scale
deflection
Polytron
®
8100 EC, 87x0 IR and 8200 CAT LC only
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”
.
Interface
Document
PROFIBUS
®
PA
Technical PROFIBUS
®
Handbook
9033782
Foundation
TM
Fieldbus FF
Technical Fieldbus Handbook
9033783
Modbus RTU
Technical Modbus Handbook
9033781
