Modbus alarm handling
Alarm list
The alarm list allows to read out the actual alarms including warnings, criticals and faults. It allows thereby - on the one hand - to display the actual alarms, and on the other it provides the basis for the system controller to react in order to avoid a compressor fault.
When power-cycling the module or providing a reset command, the inactive alarms will be cleared from the list. The alarm list is identical and shared between the IQ products CSV, CM-RC-01, CM-RC-02, CM-SW-01 and SE-i1.
Overview of the relevant Modbus registers
Register | Name | Description | Type |
|---|---|---|---|
11100 (I) | Active alarms | Number of active alarms | uint16 |
11101 (I) | Not cleared alarms | Number of listed alarms that has not yet been cleared | uint16 |
11102 (I) | Highest alarm state | Highest state of any listed alarm | uint8 |
11103 (I) | Highest active alarm state | Highest severity level of any active alarm | uint8 |
11104 (I) | Device locked | If locked, device is waiting for external reset command or restart | uint8 |
11105 (I) | Fault reset level | Reset level required to clear any active alarm | uint8 |
11201 (I) .. 11210 (I) | Alarm 1 .. 10 | Alarms are ranked in the alarm list according to severity:
Excel tool for decoding: An Excel tool which allows to decode actual alarm values received via Modbus and visualizes the decoding step by step can be downloaded here. | uint16 |
Alarm severity types
There are the following alarm severity types:
Fault 
:
If a fault alarm condition is detected, the device will open the relays for the motor contacts and stop the compressor motor.
Critical 
:
If a critical alarm condition is detected, operation may continue but for a limited time or with reduced performance.
Warning 
:
A warning is signalled when a condition occurs which may require attention but is not severe enough to stop operation of the compressor. The compressor keeps running.
Alarm reset types
Auto:
- The fault is reset automatically when the fault condition is no longer present.
Timed:
- The fault is reset automatically when the fault condition is no longer present and the configurable interval "Timed reset interval" has counted down.
- By providing a manual reset command, the timed reset interval time can be cancelled in case the fault condition is no longer present.
- Repetitive timed reset faults will be limited by the external reset faults "10-00 Too many identical timed reset faults in 24 hours" and "10-01 Too many timed reset faults in 1 hour".
External:
- In case of an external reset fault, the system must be checked before unlocking.
- The fault must be reset by reset command when the fault condition is no longer present.
Restart:
- A power cycle is required to reset the fault.
Possibilities for providing a reset command
The module can be unlocked in various ways:
- With a Modbus command (see in the BEST Software under "Documentation" --> "Modbus" --> Tab "Control & Status Word" --> Serial Control Word - this is possible even if Modbus control is not activated).
- With the BEST Software in the menu "Alarms" --> "Reset".
- Disconnect the voltage supply (L/N) for at least 5 s.
Compressor damage!
Repeated resetting of external reset faults may lead to breakdown of the compressor if the cause is not resolved.