HBM MP85A Operating Manual page 21

MP85A process controller
If the transducers are calibrated in a six-wire circuit, resistors must be activ-
ated directly into the sense lead if cable lengths are >50 m.
Four-wire connection:
full bridge
wh
bk
rd
bu
ye
Feedback bridges for four-wire configuration
Cable color code: wh= white; bk= black; bu= blue; rd= red; ye = yellow; gn= green; gy=
gray
Fig. 3.5: Transducer connection in a four-wire-configuration
NOTE
Use standard HBM cables or other shielded, low-capacitance measure-
ment cables for connecting the transducers. Connect the shield of each
transducer cable via as short a line as possible (t5 cm) and a flat
connector (4.8 mm; "Faston") on the right next to screw terminal 6.
Otherwise EMC protection is not ensured.
CAUTION
Line break detection
MP85A process controllers have line break detection for the connected trans-
ducers.
The excitation voltage lines and the measurement signal leads are monitored.
With sense leads, a wire break is only reported as a fault if both lines are
broken; with measurement signal leads and excitation voltage leads, the
break of a single line is also reported as a fault. When a single wire breaks in
a sense lead, the measured value displayed is too high.
This also means that if the connection is faulty (for example, when full bridges
or half bridges are connected in four-wire configuration and the feedback
bridges are missing) an error message appears (display: Transducer error).
A2392−5.0 en
Four-wire connection:
1
2
6
4
5
3
.
Hsg
half bridge
wh
1
bk
2
6
bu
4
gn
5
gy
3
ye
.
Hsg
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HBM