In OT, visibility comes first
You cannot protect an OT asset you do not know you have. Industrial Defender builds an inventory of controllers, servers, workstations and network devices from several sources at once (passive monitoring, active collection and configuration data) and keeps watching them against a stored baseline. Changes, vulnerabilities and compliance gaps are tied back to the same asset record.
Control systems change, grow and get hand-tuned over many years. Most plants have no current inventory: nobody knows which controller runs which software version or has which port open. Vulnerability management, change monitoring and compliance evidence then all rest on guesswork.
Common IT methods are not always suitable in OT either: legacy devices can be sensitive to active scanning. So the collection method has to be chosen to match how sensitive each environment is.