In games played under OBR, if the manager makes two trips to the mound in the same inning to the same pitcher, that pitcher must be removed Rule 8.06(b).

Is there any rule or common practice against the manager or coach going to the mound while the pitcher is warming up between innings?

I had a coach do that tonight and the other coach questioned me about it. I told him that the rule book didn't state that he couldn't so it was fine with me as long as he wasn't delaying the game. My theory being that the inning hasn't actually started until the ball is put in play so it wouldn't count as a trip.

Opinions?

The pitcher has a set amount of time to warmup between innings. If a coach speaks to the pitcher (usually a base coach, who may or may not be the head coach, who is merely crossing the infied on the way to dugout) without delaying his warmup time then I would not count a visit. I would not be a *ss about it either. If the discussion costs 10 or 15 seconds then fine, but if he stands out there discussing whatever, and interrupts his warmup time then I start subtracting in my mind. The pitcher might only get one or two warmup pitches (throw it down catcher). I have never charged a trip, but I have shortened a lot of warmups.