How should i set tool z height offset ?

There are two ways you can use the TOOL and BASE in your program.

1). Inline Form: If you are using inline forms of the motions in your program, you have to define TOOL and BASE while introducing the motion into your program.

;FOLD PTP STANDBY Vel=60 % PDAT4 Tool[7]:Gripper Base[0];%{PE}%R 8.2.24,%MKUKATPBASIS,%CMOVE,%VPTP,%P 1:PTP, 2:STANDBY, 3:, 5:60, 7:PDAT4
	$BWDSTART=FALSE
	PDAT_ACT=PPDAT4
	FDAT_ACT=FSTANDBY
	BAS(#PTP_PARAMS,60)
	PTP XSTANDBY 
	;ENDFOLD

In above code, you can see its BASE is zero and TOOL is 7.

2). You can set TOOL and BASE with an assignment before your motion command if you do not want to use inline form.

$BASE = $NULLFRAME
$TOOL = TOOL_DATA[7]


PTP STANDBY

In both cases, you are always allowed to modify the values of your BASE or TOOL as per your requirement before making an assignment.

BASE_DATA[16] = BASE_DATA[1]
TOOL_DATA[16] = TOOL_DATA[1]


BASE_DATA[16].Z = BASE_DATA[16].Z + 50;
TOOL_DATA[16].Z = TOOL_DATA[16].Z - 50;


$BASE = BASE_DATA[16]
$TOOL = TOOL_DATA[16]


PTP STANDBY

In above code, I offset BASE and TOOL by 50 mm and before doing that I kept the original value intact in BASE_DATA[1] so that you can go back to use original value if you want.

I hope this will help you to understand.

Thanks

For test make tool appear 50mm longer so robot will keep the distance from product.
lookup geometric operator

As Panic suggested, you can offset your tool by 50 or 100 mm depending on your requirement. Something like

TOOL_DATA[16].Z = TOOL_DATA[16].Z + 100;

This will give you ample space to carry out your tests.

Good Luck

TOOL_DATA[16].Z = TOOL_DATA[16].Z + 100;

That will only work if the tcp's z-axis is parallel to the flange's z-axis. So, I would rather use $TOOL = TOOL_DATA[16]:{x 0, y 0, z 100, a 0, b 0, c 0}. Also, I would rather raise the base instead of offsetting the tcp for testing paths, which can be done like this $base = $base:{x 0, y 0, z 50, a 0, b 0, c 0}