Maintenance
4.3
Symptoms
Probable Causes
Recommendations
Excessive noise or spiking in the
bus or very high signal.
Humidity in the terminal block and/or connectors
causing low signal isolation, low isolation or bad
operation power supply and/or devices and/or
terminators etc inadequate shield grounding,
excessive log or spur, inadequate amount of
terminators or noise source near the Profibus
cabling.
Check every device connector and terminal block,
and make sure that no humidity got in; detect bad
contact, if the shield cables are well ended and
grounded properly, the ripple level in the power
supply and in the bus are within acceptable values,
the terminator number and cable lengths and are
within the recommended values and also the cabling
is distant from noise sources. Check if the grounding
is adequate. If damaged devices generate noises,
disconnect one at a time and monitor the noise.
Excessive transmissions or
intermittent communication.
Inadequate cabling or spur length; power supply
voltage in the wrong device terminal block; bad
device operation; improper terminals,
inadequate shielding or grounding, the amount
of devices for spur in the network etc.
Check the cabling lengths, if the power supply
voltage of the devices is between 9 to 32 Vdc, if
there are no noise sources close to the Profibus bus.
In some situations, if damaged devices generate
noises or intermittence, disconnect one at a time and
monitor the status of the communication. Check the
communication AC signal course (750mV to
1000mV). Check the shielding and grounding
distribution. Check the number of devices in the
network and per spur.
Communication fails with some
devices.
Repeated address in the bus, feeding tension
insufficient (<9.0 Vdc), position of the
terminators, cable excess, amount of devices
besides allowed in the segment, etc.
Make sure all the devices have different addresses,
and note that when placing a device in the bus with
address 126, place it according to the configuration,
and only then include another device with address
126 in the bus. Check the cabling lengths and
amount of devices, as well as their power supply and
terminators positioning.
Intermittent powering of some or
all the equipments.
Short circuit between the bus shielding and the
terminals, defective power supply, excessive
equipment or improper amount of devices.
Check the shield isolation, the amount of devices
and their consumption, etc.
Table 4.2 – Symptoms, Probable Causes and Useful Maintenance Recommendations
Returning SMAR Products and/or Materials
Should it become necessary to return the transmitter and/or configurator to
SMAR
, simply contact
our office, informing the defective instrument serial number, and return it to our factory.
If it becomes necessary to return the transmitter and/or configurator to Smar, simply contact our
office, informing the defective instrument's serial number, and return it to our factory. In order to
speed up analysis and solution of the problem, the defective item should be returned with the
Service Request Form properly filled with a description of the failure observed and with as much
details as possible. Other information concerning to the instrument operation, such as service and
process conditions, is also helpful.
Instruments returned or to be revised outside the guarantee term should be accompanied by a
purchase order or a quote request.
