11
User Manual EE872 Modular Probe for CO
2
, RH, T and p
Decoding of float values:
Float values are stored according IEEE754 standard. The byte pairs 1, 2 and 3, 4 are inverted as fol-
lows:
MMMMMMMM
MMMMMMMM
SEEEEEEE
EMMMMMMM
Byte 3
Byte 4
Byte 1
Byte 2
Example:
Response [Hex]
Value in decimal
Byte 1 (Register 2 - Hi)
Byte 2 (Register 2 – Lo)
Byte 3 (Register 1 - Hi)
Byte 4 (Register 1 - Lo)
44
A1
0B
00
1288.34375
See also Application Note AN0103 at
.
5.3 Error Indication on the Analogue Output (NAMUR)
The EE872 features an error indication on the analogue output according to the NAMUR NE 043
recommendations (Standardization of the Signal Level for the Failure Information of Digital Transmitters,
Edition 2003-02-03, see
www.namur.net/en/recommendations-and-worksheets/current-nena.html
The feature is disabled by factory default can be enabled with the EE-PCS Product Configuration
Software, see above.
Output signal
NAMUR signal level
0-5 V
5.5 V
0-10 V
11 V
4-20 mA
21 mA
0-20 mA
21 mA
6 Maintenance
6.1 Replacing the Sensing Module EE872S
codes.
Please note:
The new sensing module EE872S must feature same CO
2
measuring range as the original EE872 probe!
If the measuring range of the replacement module and of the original EE872 probe are different, the
analogue output will stay at 4 mA, 0 V or NAMUR error indication while the CO
2
reading via RS485
interface will be 0 ppm.
Procedure:
» Power off the EE872.
» Remove the filter cap by
turning it counter-clockwise.
» Remove the sensing module by
pulling it straight out from the output unit.
» Plug the new EE872S sensing module
into the output unit.
» Screw the filter cap fingertight onto the probe.
Fig. 5
EE872 modular construction
output unit
sensing module
filter cap
