Analogue value jumping

Hi

I have program running that has a analogue signal input from a duct sensor 

the program may run for around a hour and then the Analogue value will jump from around 20 to above 50 and then cause the program to stop

the value is displayed on a KTP700 HMI and when goes over 50 displays #### instead of the numbers and then shuts then stops the program

i am not sure why this is happening and wounder if someone can see anything within my software on why this would be happening 

i have also added a pic of the sensor settings guide 

Hello andrewdaw1978

What analog value goes from 20 to 50? 

Can you describe in more details the operation? What do you mean "then shuts then stops the program"? 

For a start, you might want to check the settings at the mathematic instruction blocks. 

NIBOU

Hello andrewdaw1978

What analog value goes from 20 to 50? 

Can you describe in more details the operation? What do you mean "then shuts then stops the program"? 

For a start, you might want to check the settings at the mathematic instruction blocks. 

 Hi

i have block B006 set at my probes settings -25 to +50 

the box in the picture shows the room temp this suddenly will shoot over 50 and stop the program as if the stop button has been pressed and the fan goes off

the system is basically a duct sensor in a ducting monitoring the return temp of the room and then heats and cools when needed 

basic really apart from this small issue 

can you advise on the problem with the math blocks 

ixo65

What do you mean exactly that the program stops?

Switches the LOGO! in STOP?
If not, which temperature value will you see on the LOGO! display?

 Hi ixo65

its as if the stop button is pressed and the fan turns off

Hello andrewdaw1978

Your analog input from the duct sensor is 0-10V  or 4-20mA? 

Because LOGO! basic modules works only with an analog value 0-10V. 

For the 4-20mA you need an analog expansion module.

As i can see from the specification sheet of the sensor you can choose between the two of them.