Hi guys, I noticed that we can read a whole UDT instance (with its children) in a single system.tag.readBlocking() call, but the quality code is always good even though the quality of its children may not be.
Did anyone figure a good way to deal with that?
Within the UDT, I created an expression tag that was basically "isGood(childA) && isGood(childB) && ....", but it seems a bit fragile.
Show your code, please.
I wanted to check the quality of the children of the UDT since I wanted to add tags from other OPC sources, but right now they all come from Kepware.
Wec (aka. wind energy converter)
class Wec:
def __init__(self, identifier, wind_speed_average, status, rbh_raw_value):
self.identifier = identifier
self.wind_speed_average= wind_speed_average
self.status = status
self.rbh = Rbh(rbh_raw_value)
Initialize WECs
def initializeWECs():
results = system.tag.browse('[default]Wec')
paths = []
for x in results:
paths.append(str(x['fullPath']))
qValues = system.tag.readBlocking(paths)
wecList = []
for qValue in qValues:
value = qValue.value
identifier = value['Identifier']
goodQuality = qValue.quality.isGood() and value['IsGood']
if not goodQuality:
continue
wec = Wec(
identifier,
value['WindSpeedAverage'],
value['Status'],
value['Ctrl']['Rbh']
)
wecList.append(wec)
return wecList
UDT
{
"name": "Wec",
"parameters": {
"ID": {
"dataType": "Integer",
"value": 0
}
},
"tagType": "UdtType",
"tags": [
{
"valueSource": "expr",
"expression": "{ID}",
"name": "Identifier",
"tagType": "AtomicTag"
},
{
"opcItemPath": {
"bindType": "parameter",
"binding": "nsu\u003dKEPServerEX;s\u003dEnercon.Main.Loc.Wec.Plant{ID}.Status.St"
},
"valueSource": "opc",
"dataType": "Int4Array",
"name": "Status",
"tagType": "AtomicTag",
"opcServer": "KEPServerEX_UA"
},
{
"opcItemPath": {
"bindType": "parameter",
"binding": "nsu\u003dKEPServerEX;s\u003dEnercon.Main.Loc.Wec.Plant{ID}.Vwind"
},
"valueSource": "opc",
"dataType": "Float4",
"name": "WindSpeed",
"tagType": "AtomicTag",
"opcServer": "KEPServerEX_UA"
},
{
"valueSource": "expr",
"expression": "isGood({[.]Power})\r\n\u0026\u0026 isGood({[.]Status})\r\n\u0026\u0026 isGood({[.]WindSpeed})\r\n\u0026\u0026 isGood({[.]WindSpeedAverage})\r\n\u0026\u0026 isGood({[.]Ctrl/Rbh}) ",
"dataType": "Boolean",
"documentation": "Indicates whether all tags in this UDT has good quality or not.",
"name": "IsGood",
"tagType": "AtomicTag"
},
{
"name": "Ctrl",
"tagType": "Folder",
"tags": [
{
"opcItemPath": {
"bindType": "parameter",
"binding": "nsu\u003dKEPServerEX;s\u003dEnercon.Main.Loc.Wec.Plant{ID}.Ctrl.SessionState"
},
"valueSource": "opc",
"name": "SessionState",
"tagType": "AtomicTag",
"opcServer": "KEPServerEX_UA"
},
{
"opcItemPath": {
"bindType": "parameter",
"binding": "nsu\u003dKEPServerEX;s\u003dEnercon.Main.Loc.Wec.Plant{ID}.Ctrl.SessionSubmit"
},
"valueSource": "opc",
"dataType": "Int8Array",
"name": "SessionSubmit",
"tagType": "AtomicTag",
"opcServer": "KEPServerEX_UA"
},
{
"opcItemPath": {
"bindType": "parameter",
"binding": "nsu\u003dKEPServerEX;s\u003dEnercon.Main.Loc.Wec.Plant{ID}.Ctrl.Rbh"
},
"valueSource": "opc",
"dataType": "Int8",
"name": "Rbh",
"tagType": "AtomicTag",
"opcServer": "KEPServerEX_UA"
},
{
"opcItemPath": {
"bindType": "parameter",
"binding": "nsu\u003dKEPServerEX;s\u003dEnercon.Main.Loc.Wec.Plant{ID}.Ctrl.SessionTimeOut"
},
"valueSource": "opc",
"name": "SessionTimeOut",
"tagType": "AtomicTag",
"opcServer": "KEPServerEX_UA"
},
{
"opcItemPath": {
"bindType": "parameter",
"binding": "nsu\u003dKEPServerEX;s\u003dEnercon.Main.Loc.Wec.Plant{ID}.Ctrl.SessionPubKey"
},
"valueSource": "opc",
"dataType": "Int8",
"name": "SessionPubKey",
"tagType": "AtomicTag",
"opcServer": "KEPServerEX_UA"
},
{
"opcItemPath": {
"bindType": "parameter",
"binding": "nsu\u003dKEPServerEX;s\u003dEnercon.Main.Loc.Wec.Plant{ID}.Ctrl.SetRbh"
},
"valueSource": "opc",
"dataType": "Int8Array",
"name": "SetRbh",
"tagType": "AtomicTag",
"opcServer": "KEPServerEX_UA"
},
{
"opcItemPath": {
"bindType": "parameter",
"binding": "nsu\u003dKEPServerEX;s\u003dEnercon.Main.Loc.Wec.Plant{ID}.Ctrl.SessionRequest"
},
"valueSource": "opc",
"dataType": "Int8Array",
"name": "SessionRequest",
"tagType": "AtomicTag",
"opcServer": "KEPServerEX_UA"
}
]
},
{
"valueSource": "memory",
"dataType": "Float4",
"name": "WindSpeedAverage",
"value": 0,
"tagType": "AtomicTag"
},
{
"opcItemPath": {
"bindType": "parameter",
"binding": "nsu\u003dKEPServerEX;s\u003dEnercon.Main.Loc.Wec.Plant{ID}.P"
},
"valueSource": "opc",
"name": "Power",
"tagType": "AtomicTag",
"opcServer": "KEPServerEX_UA"
}
]
}
UDT Instances:
It seems to me that you need to recurse to get qualified values for the members of your instances.
{ And for performance sake, cache your recursive member lists--tag browsing is not something your code should be repeating all the time. }
"Reading" the base of a UDT or folder is actually an automatic read of the special computed jsonValues subproperty node. If you care about the inner qualities, you'll have to do a more specific read; the jsonValues node isn't designed to care about or return quality information.
Is jsonValues intended/designed for easily reading memory tags, where quality is not a factor?
As I understand things, it's used for some internal purpose to display the 'structure' of a tag quickly, while assuming everything within it is good quality. I think its original purpose had something to do with tag dropping in Perspective, but don't quote me on that 