Hi Robin,
[Q]: >> what's the difference between TPM20 and TBB1.
[A]: TBB1 as a transaction is used to post transaction flows and update Financial Accounting - for more details, see Post Flows - Accounting - SAP Library.
TPM20 is a standard report - Posting journal - which provides you with detailed information on the posted flows of selected transactions - see Posting Journal - Information System - SAP Library.
[Q]: >> how can we make sure TPM20 result is correct? any way to reconcile?
[A]: I don't think you need worry about that, as TRM is sub-ledger of Financials, so this integration is functionality build in the system. On the other hand, it could be a good practice, especially during the period of testing/ training to follow-up with Posting log (TPM20) after you post some flows into accounting (via TBB1, TPM44, TPM1 etc.) - so it becomes natural for Users to use that report and find relationships in the system.
and finally, TPM60 is used to calculate NPV - this result is used during valuation run (TPM1) and is transferred into accounting. so after running TPM60 + TPM1 you can find this result in the Posting journal.
hope this will help you.
Kind regards,
Renatas