TID stands for terminal ID.
TIDs are used to obtain authorisation codes from AIB Merchant Services. Each TID on your account allows you to have one open connection to AIB Merchant Services at any given time. This means that if your account has one TID, you will only be able to request one authorisation code at a time – in much the same way as a till in your local supermarket only processes one transaction at a time.
If you wish to increase the capacity of your account, this can easily be done by adding more TIDs .
Each TID on your account will be configured with one of your merchant IDs, and will process a particular type of transaction – i.e. one currency, one code capture method/code and a specific set of card types.
If all relevant TIDs are busy at the time a new request is received, error 53 will occur.