Bradley Smoker PLC-5 user manual Diagnostic Instructions, Fbc, Ddt

Instruction Set Quick Reference D-19

Diagnostic Instructions

Instruction Description

FBC

FILE BIT COMPARE

Source	#I:031
Reference	#B3:1
Result	#N7:0
Cmp Control	R6:4
Length	48
Position	0
Result Control	R6:5
Length	10
Position	0

File Bit Compare	When the input conditions go from false-to-true, the controller
FBC	compares the number of bits specified in the CMP Control
	Length (48) of the Source file (#I:031) with the bits in the
Status Bits:	Reference file (#B3:1). The controller stores the results
EN - Enable	(mismatched bit numbers) in the Result file (#N7:0). File R6:4
DN - Done Bit	controls the compare and file R6:5 controls the file that
ER - Error Bit	contains the results. The file containing the results can hold up
IN - Inhibit Bit	to 10 (the number specified in the Length field) mismatches
FD - Found Bit	between the compared files.
	Note: To avoid encountering a possible run-time error when
	executing this instruction, add a ladder rung that clears S:24
	(indexed addressing offset) immediately before a FBC
	instruction.

	DDT		Diagnostic Detect	When the input conditions go from false-to-true, the controller
DIAGNOSTIC DETECT			DDT	compares the number of bits specified in the CMP Control
				Length (20) of the Source file (# I:030) with the bits in the
Source		#I:030
			Status Bits:	Reference file (#B3:1). The controller stores the results
Reference		#B3:1
			EN - Enable	(mismatched bit numbers) in the Result file (#N10:0). Control
Result		#N10:0
			DN - Done Bit	element R6:0 controls the compare and the control element
Cmp Control		R6:0
			ER - Error Bit	R6:1 controls the file that contains the results (#N10:0). The file
Length		20
			IN - Inhibit Bit	containing the results can hold up to 5 (the number specified in
Position		0
			FD - Found Bit	the Length field) mismatches between the compared files. The
Result Control		R6:1
				controller copies the source bits to the reference file for the
Length		5
				next comparison.
Position		0
				The difference between the DDT and FBC instruction is that
				each time the DDT instruction finds a mismatch, the controller
				changes the reference bit to match the source bit. You can use
				the DDT instruction to update your reference file to reflect
				changing machine or process conditions.
				Note: To avoid encountering a possible run-time error when
				executing this instruction, add a ladder rung that clears S:24
				(indexed addressing offset) immediately before a DDT
				instruction.
			Data Transition	The DTR instruction compares the bits in the Source (I:002)
	DTR
	DATA TRANSITION		DTR	through a Mask (0FFF) with the bits in the Reference (N63:11).
				When the masked source is different than the reference, the
	Source	I:002
				instruction is true for only 1 scan. The source bits are written
	Mask	0FFF
				into the reference address for the next comparison. When the
	Reference	N63:11		masked source and the reference are the same, the instruction
				remains false.

Publication 1785-UM012D-EN-P - July 2005