# Deciphering overflow and underflow conditions coming from Analog inputs **URL:** \ **Category:** Ignition\ **Tags:** vision\ **Created:** [July 27, 2023, 6:53pm UTC](https://forum.inductiveautomation.com/t/deciphering-overflow-and-underflow-conditions-coming-from-analog-inputs/77035 "2023-07-27T18:53:27Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Kevin\_Zornes](https://avatars.discourse-cdn.com/v4/letter/k/ee59a6/32.png) [@Kevin\_Zornes](https://forum.inductiveautomation.com/u/Kevin_Zornes)\ **Post date:** [July 27, 2023, 6:53pm UTC](https://forum.inductiveautomation.com/t/deciphering-overflow-and-underflow-conditions-coming-from-analog-inputs/77035/1 "2023-07-27T18:53:27Z")
Is there any way to ignore underflow and overflow signals coming from a PLC. Seems that tags don,t know how to decipher this. ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [July 27, 2023, 6:55pm UTC](https://forum.inductiveautomation.com/t/deciphering-overflow-and-underflow-conditions-coming-from-analog-inputs/77035/2 "2023-07-27T18:55:18Z")
Can you elaborate? ---
**Author:** ![Kevin\_Zornes](https://avatars.discourse-cdn.com/v4/letter/k/ee59a6/32.png) [@Kevin\_Zornes](https://forum.inductiveautomation.com/u/Kevin_Zornes)\ **Post date:** [July 27, 2023, 7:28pm UTC](https://forum.inductiveautomation.com/t/deciphering-overflow-and-underflow-conditions-coming-from-analog-inputs/77035/3 "2023-07-27T19:28:34Z")
I am reading an input word from a Seimens S7-1200. When the field device is in active, below 4 ma underflow the input word goes negative. The tag displays a positive number outside of the engineering High limit set. ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [July 27, 2023, 7:29pm UTC](https://forum.inductiveautomation.com/t/deciphering-overflow-and-underflow-conditions-coming-from-analog-inputs/77035/4 "2023-07-27T19:29:47Z")
What datatype is the Ignition tag set as and what is the address (OPC Item Path) you used? ---
**Author:** ![Transistor](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/transistor/32/3380_2.png) [@Transistor](https://forum.inductiveautomation.com/u/Transistor)\ **Post date:** [July 27, 2023, 7:31pm UTC](https://forum.inductiveautomation.com/t/deciphering-overflow-and-underflow-conditions-coming-from-analog-inputs/77035/5 "2023-07-27T19:31:28Z")
> [@Kevin\_Zornes](#): > > When the field device is in active, below 4 ma underflow the input word goes negative. The tag displays a positive number outside of the engineering High limit set. How can it be negative and postitive at the same time. Can you write the problem more clearly? ---
**Author:** ![Kevin\_Zornes](https://avatars.discourse-cdn.com/v4/letter/k/ee59a6/32.png) [@Kevin\_Zornes](https://forum.inductiveautomation.com/u/Kevin_Zornes)\ **Post date:** [July 27, 2023, 7:33pm UTC](https://forum.inductiveautomation.com/t/deciphering-overflow-and-underflow-conditions-coming-from-analog-inputs/77035/6 "2023-07-27T19:33:54Z")
I have the data type set as float. In this specific case the item patch is set up as [Grinding PLC]IW96. as per instructions on connecting to a Seimens device. ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [July 27, 2023, 7:37pm UTC](https://forum.inductiveautomation.com/t/deciphering-overflow-and-underflow-conditions-coming-from-analog-inputs/77035/7 "2023-07-27T19:37:50Z")
`IW96` is an _unsigned_ type. If you're expecting to see negative values you need a signed type. Try `II96`, and see the [address syntax reference here](https://docs.inductiveautomation.com/display/DOC81/Siemens). Further, if you're actually expecting a floating point value, then neither of these types are correct. ---
**Author:** ![Kevin\_Zornes](https://avatars.discourse-cdn.com/v4/letter/k/ee59a6/32.png) [@Kevin\_Zornes](https://forum.inductiveautomation.com/u/Kevin_Zornes)\ **Post date:** [July 27, 2023, 7:43pm UTC](https://forum.inductiveautomation.com/t/deciphering-overflow-and-underflow-conditions-coming-from-analog-inputs/77035/8 "2023-07-27T19:43:10Z")
That worked. I changed the tag to integer and OPC to II96. Thank you very much.