I notice that when I reassign the alarm to the SD user again, the incident ticket's CA Service Desk Field becomes updated with new value.
I would like to know how can I stop casdgtw probe from updating incident ticket's CA Service Desk Fields.
The casdgtw probe is no longer supported. You may want to start looking at the sdgtw probe soon.
I believe this is working as designed. The create ticket action will create a new ticket when an alarm is assigned.
The "sdgtw" probe will listen for "alarm_assign" and create a ticket.
However, there is a configuration parameter called: "CA UIM Users for Alarm Processing" where you can specify only specific UIM users to process alarms for. That may be an option.