ABB AC500 Introduction Manual page 68

Figure: Disassembly of the FBP Terminal Unit (TU505 or TU506)
Step 3: Mounting of the I/O Terminal Unit (TU515, TU516, TU531 or TU532)
Figure: I/O Terminal Unit assembly (TU515, TU516, TU531 or TU532)
The I/O Terminal Unit is installed on the DIN rail in the same way as the FBP Terminal Unit. Once
secured on the DIN rail, slide the I/O unit to the left until it fully locks into place creating a solid
mechanical and electrical connection.
Up to 7 I/O Terminal Units could be combined with a FBP Terminal Unit.
ATTENTION
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G1
Introduction to AC500
When attaching the FBP, FBP Interface and I/O modules, make sure the bus
connectors are securely locked together to ensure proper electrical connection.
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AC500 / Issued: 07.2006