Proworx - how to read firstscan bit

I have a modicon A984-145 compact and using proworx32. I am new to modicon programming and find it challenging to do the simplest tasks. Anyway, I am trying to read the firstscan bit by using the stat function block. My top node is 40050 and i set the length to 3 words. The first scan bit is located in the 3rd word, bit 1. Therefore, it would be address 40052/01.

When I use a contact in my rung and insert this bit into the address I get an error (invalid reference number or range....).

How do I do this?

Thanks!

I feel bad for you if you are using Proworx32. That really bites.

Addressing single bits in a word address in Modicon is not as straight forward as something like 40052/01. Use the SENS instruction to determine the status of a bit in word 40052. Proworx32 online help should show you how to configure the instruction. You will then have to output the SENS line (second line down from right hand top of function block) to a coil. Then use that coil address as your first scan in your program.

-------+----------+-

       |SENS      |

       |A        1|        FIRST_SCAN

      ++B    40052+----------(  )----

       |C        1|

       |          |

      -+----------+-

It might be simpler for you to configure an unconditional coil in row 1 of the first network in your scanned program (which doesn't necessarily have to be network 1) and then use a rising edge contact -]^[- instruction addressed to that coil for first scan detection.

One more thing - do not forget that Modicon 984 networks are solved by column first. So if you put logic right under the SENS block it is going to get scanned before the coil gets set/cleared.

And welcome to the forum, that's a great user name.