bgtorque
Member
In my program my program tags largely exist in a couple of a data blocks. There are a number of tags in there that the operator may need to get to in order to change the value, so for alarms the high and low alarm and trip levels (so that is 4 tags per channel), or for the scaling calibrations the gain and offset values.
I am struggling to get my head around ‘Start Value’, Default Value’, ‘Retain’ and ‘Setpoint’ values. I have mapped over the alarm, trip and calibration tags to the HMI and can change the values with a mapped I/O field, but when I go live I can see that these values are just held in the ‘Monitor Value’. Should the PLC go off-line then it will then go back to the default or ‘Start Values’. I guess what I’m asking is how can I have an operator with access to the HMI, permanently overwrite a tag starting value that the PLC will hold in its non-volatile memory?
as always, cheers for any pointers.
I am struggling to get my head around ‘Start Value’, Default Value’, ‘Retain’ and ‘Setpoint’ values. I have mapped over the alarm, trip and calibration tags to the HMI and can change the values with a mapped I/O field, but when I go live I can see that these values are just held in the ‘Monitor Value’. Should the PLC go off-line then it will then go back to the default or ‘Start Values’. I guess what I’m asking is how can I have an operator with access to the HMI, permanently overwrite a tag starting value that the PLC will hold in its non-volatile memory?
as always, cheers for any pointers.