GE 90-30/20/Micro manual Alwon

4

A common application is to scale analog input values with a MUL operation followed by a DIV and possibly an ADD operation. With a range up to 32000, using a MUL INT will overflow. Using an %AI value for a MUL DINT will also not work as the 32-bit I1 will combine 2 analog inputs at the same time. You must move the analog input to the low word of a double register, then test the sign and set the second register to 0 if positive or –1 if it was negative. Use the double register with the MUL DINT for a 32 product for the following DIV function.

For example, the following logic could be used to scale a +/–10 volt input %AI1 to +/– 25000 engineering units in %R5.

		_____			_____			_____
ALW_ON
——] [——— MOVE————————————————— MOVE————————————————— LT_									——————————<+>
		INT			INT			INT
%AI0001–IN			Q–%R0001		CONST –IN	Q–%R0002 %R0001 –I1			Q-
		LEN			+00000 LEN
		00001			00001
		_____			_____		CONST –I2
							+00000	_____
		_____
<+>—————MOVE_–
		INT
CONST –IN			Q–%R0002
–00001 LEN
		00001
		_____
				_____				_____
ALW_ON
——] [——————————— MUL_————————————————————————————————— DIV_–
				DINT				DINT
		%R0001 –I1 Q–%R0003					%R0003 –I1		Q–%R0005
		CONST –I2					CONST –I2
	+0000025000			_____			+0000032000	_____

4-30 Series 90-30/20/Micro Programmable Controllers Reference Manual–September 1998 GFK-0467K