MR MESSKO COMPACT - General Malfunctions (Type TT)

9 Fault elimination
955831400/02 EN
Checking the plausibility of the measured values
If the device is working but not reporting plausible values, check, document
and compare the following:
▪ Measured value via 4...20mA analog output
▪ Measured value via Modbus RTU interface
▪ Measured value via pointer on the scale
▪ Actual physical measured value (measured or estimated).
Calculating the target current of the 4…20mA analog output
► I
target
= 4mA + 16mA * [(current measured value scale - scale
min
) / (scale-
max
- scale
min
)]
Calculation example for the oil temperature indicator:
▪ Scale of -20…+140°C; the indicator points to 60°C
=> I
target
= 4mA + 16mA * [(60°C - -20°C)/(140°C - -20°C)]
= 4mA + 16mA * 0.5
= 12mA
9.1 General malfunctions (type TT)
You are using a device with passive 4…20mA analog output.
Characteristics/
details
Cause Remedy
No function
(4...20mA)
Power supply not present ▪ Check cables
▪ Check power supply (18…
30VDC)
▪ Check 4…20mA receiver
(loop into multimeter)
Table9: General faults