temperature control via S7

[sparkotronic]

Hi all, I'm looking for a bit of advice. I've been asked to put a control system in place to regulate the heating in one of our production halls. I have previously installed a compressed air managment system and I want to integrate it in to this panel. I'm not sure what to use for the feedback of zone tempretures. My manager wants each zone temp to be displayed on a HMI and also to have set point adjustments on the HMI. I'm ok with the programming side, I just not to sure whaich type of temp sensors to use. Should feedback be 4-20mA/0-10V? Each zone is about 50-100 meters away from the control panel. I see that Siemens supply Tempreature control modules for the 300 range of PLC's, would this be the best way to go? Thanks in advance, Colin

[JesperMP]

Avoid 0-10V. The widely used industry standard is 4-20 mA. A distance of 100 m is no problem with a 4-20 mA sensor. For temperature measurement, the alternative could be Pt100 sensors going into dedicated Pt100 analog inputs. You need to pull all 4 wires the whole way to the sensor to facilitate the wire compensation. The use of 4-wire cables means that this option is actually more expensive than 4-20 mA.

[sparkotronic]

Thanks for the advice, I'll need to have a look at some sensors now.