PCS1800 PLC 12*slot Rack Module

Manage PLC Channels plc rack and slot Typically, the first two leftmost slots are dedicated for the power supply and CPU PLC hardware modular base configuration One question to 12 coins slot When PLC rack is inserted in PLC manager, slots startwith number 1 If I use Allen-Bradley PLSs, the module numbers start with 0

main slot 303 PLC output interface module?, With reference to a PLC: What is a remote rack In what way does tag-based addressing differ from rackslot-based addressing?