Easy Chart - One tag, pen per bit

Ignition
1

Is there a way to store history for an integer tag and then reference one bit of the integer to create multiple pens on a easy chart?

The problem is easy chart takes in a tag path and creates the chart from that path. I don’t see how I could use getBit() or write some script to pass in the bits that I want.

2

There are times when the Easy Chart is not so easy. I don’t think there is a way to do what you’re looking for with the Easy Chart Component.

You could do this in the standard Chart component with some scripting.

  • Query the Tag History
  • Loop through the return data set
  • For each value of the tag convert to a Binary List
  • Create a Data set to hold the value of each bit at the given time stamp
  • Move the data set into the chart for display

That would look something like the following. Please note this has not been completely tested.

#defining a function to do the decimal to binary conversion
def dec2Bin(intValue,intNumBits=0,leftToRight=False):
	
    intNumBits = abs(intNumBits)
	seqBits = []
	while intValue != 0:
		seqBits.append(intValue % 2)
		intValue = intValue/2
		
	if len(seqBits) < intNumBits:
		while len(seqBits) < intNumBits:
			seqBits.append(0)
	elif len(seqBits) > intNumBits and intNumBits != 0:
		while len(seqBits) > intNumBits:
			seqBits.pop()
	
	
	if leftToRight:
		seqBits.reverse()
	
	return seqBits

#grab the tag history for the last 30 mins		
endTime = system.date.now()
startTime = system.date.addMinutes(endTime, -30)

tagData = system.tag.queryTagHistory(paths=['integerTagPath'], startDate=startTime, endDate=endTime, returnSize=-1, aggregationMode="Maximum", returnFormat='Wide')

#the tagData data set will have the columns ['t_stamp', 'integerTagPath']
#we want to take the tag value at each t_stamp and expand it to the number
#of bits we're interested in

#for the sake of clarity I'm keeping the number of bits low
numBits = 4

headers = ['t_stamp','bit 0','bit 1','bit 2','bit 3']
chartData = []
for ts in range(tagData.rowCount):
	newRow = [tagData.getValueAt(ts,'t_stamp')]
	
	#get the bit values for the value from tag history
	bits = dec2Bin(tagData.getValueAt(ts,'integerTagPath'),numBits)
	
	for bit in bits:
		newRow.append(bit)
	chartData.append(newRow)

#now you have a data set relating the bit values
#to the time stamp from history
#just set the Chart Components Data property equal to
#this data set