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 --> 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. In case the BEST converter is connected, it must be plugged off as the BEST converter also provides supply voltage to the module for communication purposes.
Compressor damage!
Repeated resetting of external reset faults may lead to breakdown of the compressor if the cause is not resolved.