I haven't had any problem installing the jet direct into the pump module. The slot exist because it is a common place to put it. I have used a lot of non-Agilent (Leap... Now Agilent?) autosamplers and the communcations are best routed thru the pump. I agree that the DAD is the module of choice these days if you have it but I haven't had any more trouble with pump LAN than DAD LAN.