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Click Here to Learn More!The HI 1746WS excitation error occurs when the resistance of the load cell system changes from what it was during the last calibration (did you add or remove a load cell?).
In a new installation an excitation error would be normal until the first calibration was completed successfully.
The module having an excitation error would not prevent the unit from responding to weight changes on the scale.
If there is a problem on the scale, however, it might account for an excitation error. If this is the case it could be that the module is not responding to weight changes. This could be a result of a wiring error on the load cells system, or a setup problem in the module programming.
To troubleshoot to determine a wiring problem perform the following:
1. Measure the excitation voltage from the module. This is between pins 2 and 7 on the connector. This should be +5v, reference to pin 7 (neg exc).
2. Measure the sense voltage between pins 3 and 6 on the connector. This should also be +5v, reference to pin 6 (neg sen).
3. Measure the signal voltage between pins 4 and 5 on the connector. This should range between 0 and +15 mv reference to pin 5 (neg sig).
4. Change the weight on the scale while monitoring the signal voltage. The mv reading should increase with an increase in weight.
If all the voltages are good and the polarity is correct, and it responds properly to weight changes, signal mv increases with increased weight, then the load cells are probably OK.
If any of the voltages are incorrect you will need to determine the cause and correct the problem before the module will work properly.
Once you verify that the voltages are correct you should be able to see a change in the weight reading with changes in weight on the scale. If the weight reading does not change, then a calibration cannot be performed.
If the problem is a setup problem, it is normally a problem with the parameter settings. The most common error made is to write the parameters in one format (integer) when the module is working in another format (float). The Multiplier determines what format the module will be working in. The Multiplier is the SLC Output table, word 15. If this value is "0" then the module is working in floating point values and all parameters written to the module need to be in floating point format. If the Multiplier is non-zero, then the module will work in integer format and all parameters then need to be in integer format. If the module is working in floating point format and the values are written to the module in integer format, they will normally be interpreted as "zero"
The simplest way to troubleshoot this type of problem is to:
1. Set the Multiplier (Output word #15) to a value of "1". This will cause the module to operate in integer format with no decimal place resolution.
2. Do a "COPY" command with a source of M1:x.28 (where x is the slot number for the module), and a destination of some integer location with non-used registers, and a length of 37. This will copy all the parameter values as set in the module into your integer file.
3. Compare these values with the list of parameters on page 4-4 of the manual. Each of the first parameters, marked with "(float)" after the parameter name are all 4 bytes (2 words). You will have the first word as the Most Significant Word (MSW) and the second is the Least Significant Word (LSW). (NOTE: the Dead Band 1 -- word 36 parameter is missing from the list in older manuals.) Each of your values in the first 24 words copied will probably be 0 in the MSW (first of two words per parameter) and the second, LSW, should show you the value as set. The second half of the list (marked with "(int)") are integer values and will only consist of one word each.
4. If the parameters are not as yo
