sensors specs

[otrotabi]

There are very different types of temperature sensors listed on the hardware guide for TM172. 

Two questions:

1) what is the criteria to select NTC or PT1000 ? Range is the same for both types.

2) depending on the beta values, the input configuration should be selected accordingly. I have not been able to find which beta value corresponds to the TM1ST sensors (I have used Cfg_Aix = 0 before). Is that ok ?

[Bastian_Schmitz · Accepted solution]

All NTC Sensors in the SE offer are Beta 3435 (=2).

The NTC Sensor Beta 3977 (=0) is only available as Eliwell product.

This type is normaly used as compressor discharge temperature probe.

The "normal" NTC (=2) could not measuer such high temperatures, he stopped at ~120°C.

The PTC sensor is also not available as SE product, and the full type is KTY81-121

The Sensors of the SE Building portfolio has different beta values and could be used with additional librarys.

I prefere to use the NTC probe. This sensor is together with the M17x PLCs more accurat then a PT1000 probe. And the NTC sensors are less cost intensive. The PT1000 function is usefull if you need for your application a special sensor which will be manufractured from a third party supply. In that case everbody understand a PT1000 element, but not everybody could deliver the needed NTC probe with the correct BETA value. 

If you use the standart SE NTCs, and configure them as 0 you will always get problems with the accuracy. An offset will only work at one fixed point. That is the reason why the AI configuration use as standard 2 and not 0.

[otrotabi]

Thanks for your detailed explanation. I wrote "Cfg_Aix = 0" but actually I did so from memory. I have been using the default value so far which is Cfg_Aix = 2, so I am on the safe side.

We did buy some PT1000 TM1STPTTSN52050 once which are on our warehouse. From your answer I will go ahead and use them.