Surgical stapling system comprising a jaw attachment lockout

An end effector of a circular stapling instrument, said end effector comprising:

• a frame;
• a cartridge body including staple cavities;
• staples removably stored in said staple cavities;
• and
• a closure drive, comprising:
• an anvil configured to deform said staples;
• a trocar shaft movable between a retracted position and a fully-extended position;
• and
• means for blocking the attachment of said anvil to said trocar shaft when said trocar shaft is not in said fully-extended position.

An end effector of a circular stapling instrument, said end effector comprising:

• a frame;
• a cartridge body including staple cavities;
• staples removably stored in said staple cavities;
• and
• a closure drive, comprising:
• an anvil configured to deform said staples;
• a trocar shaft extendable between a retracted position and a threshold position;
• and
• a connector configured to prevent said anvil from being attached to said trocar shaft when said trocar shaft is not extended to said threshold position and configured to permit said anvil to be attached to said trocar shaft when said trocar shaft is extended to said threshold position.

A circular stapling assembly, comprising:

• a frame comprising a distal seat;
• a firing drive;
• a replaceable cartridge, comprising:
• a connector engageable with said distal seat;
• staple cavities;
• and
• staples removably stored in said staple cavities, wherein said firing drive is configured to eject said staples from said staple cavities during a firing stroke of said firing drive;
• a sensor configured to detect whether said replaceable cartridge is properly seated in said distal seat;
• and
• a lock configured to prevent said firing drive from performing said firing stroke if said sensor detects that said replaceable cartridge is not properly seated in said distal seat.

A stapling assembly, comprising:

• a staple cartridge comprising a cartridge body and a plurality of staples removably stored in said cartridge body;
• a shaft comprising a frame, wherein said cartridge body is attached to said frame when said staple cartridge is assembled to said shaft;
• and
• a firing drive, comprising:
• a first drive member;
• and
• a second drive member, wherein said second drive member is movable between a first position in which said second drive member is not operably engaged with said first drive member and a second position in which said second drive member is operably engaged with said first drive member, and wherein said staple cartridge is configured to push said second drive member into said second position when said staple cartridge is assembled to said shaft.