envea STACK 602, Руководство пользователя

Страница: 54 / 68

9 Maintenance STACK 602
54
(PC-000848-MA Issue 5, December 2021)
ENVEA UK Ltd
9.5.6 Frozen Readings
If a sensor reading is not updating, this could have several causes.
1. If there is also a ‘No Response’ alarm, this could be due to:
1a. A communication problem that must be fixed (see sections above)
1b. A faulty sensor PCB, which needs to be replaced.
2. If there is no such alarm, then:
2a. The sensor may be running a self-test (go to QA/Self Tests to check
this).
2b. The sensor may have been disabled (select Sensor Setup | More
Settings | Edit an Existing Device and check the Enabled setting).
2c. The sensor may be in Plant Stop mode. The word ‘STOP’ will be
displayed underneath the sensor reading.
2d. The control unit may be too busy reading other sensors. To solve this,
power the control unit OFF and back ON; the control unit will restart
sharing its time between all sensors on the network.
9.5.7 Troubleshooting Opacity
Symptom Cause and Solution
‘ Light Normal ’ level has
dropped significantly
below the setup level
See section 9.5.8 below for likely cause (Step 2b)
and instructions on how to resolve this issue.
If this does not resolve the problem, please
contact ENVEA or your local ENVEA
representative.
‘ Light Normal ’ has
reached a fixed,
saturated level (118)
See section 9.5.8 below for likely cause (Step 2a)
and instructions on how to resolve this issue.
If this does not resolve the problem, please
contact ENVEA or your local ENVEA
representative.
Opacity Light OFF = FAIL
(Opacity alarm is shown)
Please contact ENVEA or your local
ENVEA representative for assistance.
Opacity Light 50% = FAIL
(Opacity alarm is shown)
9.5.8 Sensor Reading too Low or too High
The control unit gets the reading from the sensor using digital Modbus communi -
cation, which has error checking. Therefore, if a reading is being displayed at the
control unit without any ‘No Response’ message (and not frozen – see section
above), you can be confident this is a genuine reading from the sensor.
If it is not the reading you expect, consider the following:
1. Run the sensor self-checks manually and follow the troubleshooting advice
given in section
9.5.7
above.
2. Check the main Setup screen. The sensor must be set up with the Receiver
light level within the instrument range. Two common problems can occur: