LMN of FB58 suddenly "railing" to 100% in auto

Hello everyone,

     I'm having trouble with a temp PID that's suddenly sending 20mA to the actuator even when the error is very small—steady state already reached. The analog oputputs of the PLC are also behaving really strange, sending 20mA when LMN is 0, but that'll be subject of another topic. I asked a screen to be made in the SCADA with all the important variables of the PID, and the LMN is actually getting the value of 100%—or the limit set. Nothing's been changed in the PID because I downloaded again the original project and in the SCADA I'm the only one with access to this screen, but still the LMN is doing this after months of working properly.

Has any of you seen something like this? What could be causing it?

Thank you very much in advance, I really need to get this to work again.

Hi karkas,

could you provide us more Information? like:

• Which product is causing a problem? (Insert article number)

• Which version do you use in the project? (version, service pack, update)

BR,

Noodles

 Hi Noodles, 

I took long to answer because I wasn't getting notifications and thought no one replied.  The software version for the development was STEP 7 Professional V5.5 SP1. It is a 314-2DP CPU. I don't have the article number right now with me, but do you think the cause could be related to it? I'll find it and post it. 

As for the product that's causing the problem, I really don't know if it's because of a specific one. 

Thank you very much in advance.

8Noodles

Hi karkas,

could you provide us more Information? like:

• Which product is causing a problem? (Insert article number)

• Which version do you use in the project? (version, service pack, update)

BR,

Noodles

it is called the bumpless transfer from manual to auto mode . try to search for this on the forum 

bumpless transfer