The Met One Modbus driver has 7 individual error codes, this article will go into more detail of each error code and explain the reasons for the error.
The values are ‘bit encoded’, and will be added together to generate a composite number. For example 10 implies both flow (2) and relative humidity (8) failure have been detected.
Error Code 1 – Calibration error
An error code 1 returned by a Modbus 6000 series counter means that the calibration voltage has deviated beyond the operational tolerance of 1V ±0.2V. The calibration voltage can be described as a measurement of the background level of light within the particle counter. At the time of manufacture this will be set up to the nominal 1V. Any significant change in this measurement can almost exclusively be attributed to either sensor contamination or laser failure. Laser failure normally results in the calibration voltage dropping below 0.8V as the laser becomes less efficient and is no longer able to maintain a sufficient level of light within the sensor. Contamination normally results in the calibration voltage increasing as contaminants cause additional light scatter within the sensor.
If an error code 1 is seen but then clears, the most likely cause is dry contaminants that have caused additional light scatter whilst they are in the sensor but that effect has lessened as the contamination has cleared or been pulled out of the internal monitoring environment. If the error is only seen for a short time then the counter can continue to be used but should be monitored closely to ensure it does not occur repeatedly.
Resolution:
If any counter has spent significant time with an error code 1 or repeatedly returns this status, even if only for short periods, then it is recommended that the counter be removed from operation and investigated. Counters that have suffered significant contamination will often require large threshold adjustment at calibration which can result in ‘As Received’ failures. The sooner the counter is investigated and cleaned, (if necessary) the less likely that there will be ‘As Received’ calibration failures and the more likely that the counter can be fully repaired.
Error Code 2 – Flow error
A flow error is returned when when the particle counter is receiving either too much, or not enough flow.
Resolution:
To resolve a flow error you would need to measure the current flow to determine if it was either high or low flow. If the flow is high, you can try adjusting it on the pump itself until you have the correct amount. If the flow is low, you can try adjusting the pump or checking for any kind of blockage or bends in the tube.
Error Code 4 – Temperature error
A temperature error will be given when there is a problem communicating with the Temp/RH probe attached to the Met One counter.
Resolution:
Ensure that the connection to the probe is correct on both sides and that the plug is securely in place.
Error Code 8 – Relative humidity error
You will receive a relative humidity error when there is a problem communicating with the Temp/RH probe attached to the Met One counter.
Resolution:
Ensure that the connection to the probe is correct on both sides and that the plug is securely in place.
Error Code 16 – Air velocity error
An air velocity error will appear if there is a problem communicating with the attached air velocity sensor.
Resolution:
Ensure that the connection to the sensor is correct on both sides and that the plug is securely in place.
Error Code 32 System Alarm error
A system alarm error means there is a direct fault with the counter itself.
Resolution:
The resolution to this problem will be returning the counter to the supplier or to Hach.
Error Code 256 Communications error
A communications error will appear when the enVigil software has no contact with the particle counter.
Resolution:
A communications error can mean multiple problems. The first thing to do is check the wiring to the sensor to make sure it is correctly connected.