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EPLC100- Zirconia Blocks

Hello,

We have two nos of Oxygen probe high impedance voltage inputs and wanted to connect to single process control instrument with integrated display and compare, control the "Zirconia Control Process Value" from two different oxygen probes.

Can it be possible in 3500/2604/2704 series controllers or need to go for EPLC100 wherein can we connect two O2 probe inputs?
How many Zirconia Blocks can be supported in EPLC100?

Please do the needful.

Thank you.

Regards,
Sujit Jejurkar
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  • Stephen Daly (Software Support Engineer) February 18, 2019 10:14
    Hi Sujit,

    The discrete controllers you mention are only have one Zirconia block available, so you are limited to using one probe.

    However there is no limit to the number of Zirconia blocks you can use in the E+PLC range.
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  • Ian Roughsedge (Product Manager - Systems) February 25, 2019 13:48
    Hi Sujit,

    Stephen mentioned the E+PLC range in the reply above and to complete the picture the following may be useful to you.

    For a good quality reading from a Zirconia probe, the real electrical mV measurement analogue input (AI) must have a high impedance, higher than that needed for many other types of inputs such as Thermocouples.

    The E+PLC100 has 4 AI, each with the same electrical characteristics and they all include the necessary high impedance for use with a Zirconia probe. In a typical Zirconia probe application, where there is a temperature reading from a thermocouple as well as the probe mV reading, you need two AI per probe. Therefore the 4 AI of the E+PLC100 well suits the two probe application you mention.

    For the E+PLC400, which is a modular PLC, there are two card types that have the necessary high input impedance: the ZI (Zirconia) module and AI2 (2 channel analogue input) module. For both module types, only the second channel has the high impedance required for a Zirconia probe. This means an E+PLC400 using all 16 I/O slots in the largest base exclusively for zirconia probes, it could accommodate up to 16 probe readings.

    As Stephen states, for all E+PLC in the range, there is no numeric limit to the number of Zirconia function blocks, and although ultimately memory use would come into play at some point, that would be so far away from the limit linked to electrical I/O that you can take it to mean 'no limit'.
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  • Hello Ian,

    Thank you very much for the useful technical information.

    Regards,
    Sujit Jejurkar
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