AOA,
@cowboy
Brother no one could/would tell you the exact duties involved in these posts i.e S.I,ASI etc. However this is mainly a field job very very less desk duties involved. You will have a variety of tasks to perform according to the needs and situation of that time.

Since civilian officers/staff remains within the domestic jurisdiction of their country,they do not get fixed routine duties everyday/month. Duties/tasks could be vary as and when detailed by the organization.

One thing is for sure that the organization's domain is vast,so you can expect to perform duty in any given field of that domain.Some seniors also says that individual gets appointments/postings after a thorough analysis of individual's psychological,mental,personal abilities,aptitude etc by the organization.

This is my personal view and an unauthentic information,like I said no body would be able to divulge exact nature of such duties in details.

Good Luck

Regards