I have an 8 point analog input card on a rack with a SLC 5/04 CPU. It has been in operation for 20 years or so. There have been some power problems at site lately and ever since they fixed them I have been having issues with 3 of the 4-20mA circuits on this card showing open circuit. I have had my meter on them when they show open circuit. The signal reads 3.96mA, just below the 4mA minimum and boom, the machine goes down. Is there a way to adjust this tolerance?? I don't think there is anything wrong with the 3 transmitters so the error is just a nuisance.