Troubleshooting - OJ Electronics TTH-620 Serie Installation

TROUBLESHOOTING

Symptom
No communication between
controller and TTH-620x
Incorrect temperature
measurement
2
Cause
Broken or poor connection
Wrong Modbus address
Wrong Modbus communication
parameters
Defective receiving unit
Defective TTH-620x
Measuring hole in TTH-620x is
dirty or the free, unobstructed
passage of air through the hole
is impeded in some other way
Incorrect scaling of
measurement signals in receiving
unit
Incorrect positioning of TTH-
620x within the duct
Defective TTH-620x
Action
Check that cable and connectors are connected properly.
Check that any joints and extension cable are connected properly.
Set the correct Modbus address and Modbus communication parameters in the
receiving unit. TTH-6202 has Modbus address 170.
Set the correct Modbus address and Modbus communication parameters in the
receiving unit. The communication protocol for the TTH-620x series is 38.4 kbaud, 1
start bit, 8 data bits, 1 or 2 stop bits and no parity.
Replace receiving unit.
Replace TTH-620x.
Remove dirt or other material preventing free, unobstructed passage of air through the
measuring hole.
Check and, if necessary, adjust scaling of measuring signals in receiving unit. The
measuring range for temperature is 40°C to +85°C (res. 0.01°C).
Check the physical position of TTH-620x within the duct. Wherever possible, the TTH-
620x measuring hole should be positioned close to the centre of the duct. The sensor
should be installed in such a way that the air flow in the duct can pass unhindered
through the measuring hole at the end of the sensor, which should be aligned parallel
to the air flow.
Replace TTH-620x.
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