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IM-ENG-116/GB
8. M
AINTENANCE AND
T
ROUBLESHOOTING
8.1 Maintenance
No periodic maintenance or calibration is required for this product, which is also not intended for direct repair from
the end-user. For these reasons, the Mux 2700 enclosure was not designed to be easily opened (and a special tool
is in fact required at this purpose).
Warning !
Any attempt to open the unit or to directly repair it will make the warranty null and void.
8.2 Off-line self-test procedure
This the first recommended check when there is any doubt about proper Mux2700 operation.
•
With the power off – and no connection on the serial line (RS-485) port – set SW8 to the Test position.
•
When the Mux2700 is powered, the three LED should light for about 1 second each in sequence (Red, Yellow,
Green…). If this is not the case, the unit should be returned to Elcon for repair.
After having completed the self-test procedure, switch the power off and put SW8 back into the Normal position.
8.3 Additional troubleshooting
When the unit pass the off-line self-test procedure and there are still operational problems, the following checks
should be performed:
•
Verify that the power-up sequence – as described in section 3.4 – to get more information about the situation.
When the Red LED is always fixed On at power-up, the unit should be returned to Elcon for repair.
•
Repeat the checks described in section 7.4 to identify possible problems.
•
When you have signal level problems, verify that the equivalent, parallel network resistance is at least 200
Ω
(250
Ω
recommended) as required by the Hart specifications.
•
When the communication with the Maintenance Workstation is OK but you can not communicate with the field
devices, check with an oscilloscope the Hart signal level and noise content on the loops.
•
With a relevant noise present at the Hart signal level – and when it is not viable to reduce it in any other way –
you can consider the increase of the loop series resistance up to 500
Ω
(when compatible with the DC 4/20 mA
loop requirements). In this way, the Hart signal level double, as well as the signal-to-noise ratio
Note:
Elcon technical support is available to advise about special problems or unclear situations. Please always contact
Elcon before returning any suspected defective unit, either in warranty or not.
