MOSCAD analog raw input wrong

Hello all,

after finishing throwing rotten tomatoes at the screen please help me .

I have a MOSCAD system from Motorola which somehow reads all raw analog inputs as "equal". For example, if I program the analog output at the station for active power then all my raw inputs show around 1330, if for current then 800, etc.

I can calculate the engineering values once I get the raws right, but its all wrong.

Since my inputs are 4-20mA I put LV=800 and HV=4095 at the output station.

It sounds like you haven't linked your IO correctly or possibly linked the one Analog to all IO points. I deal with MOSCAD a great deal and may be able to help with a little more info.

IO linking will bite ya in the ole buttocks on a MOSCAD. Can you get a "screen capture" of the IO link for that particular AI card? It might show us a problem you have with the link.

Also, high value on a MOSCAD AI card is 4000, not 4095. 4 -20 mA will read 800 - 4000. Are you seeing an OF (Overflow) or UF (Underflow) on the status LED's on the card?

thx for reply guys,

I attach my AI, however I don't think its wrong. Also on the HW test AI_1 is voltage, AI_2 is frequency, and all others is power. In reality, the power values should be really different from each other.

Can it be that I put the LV and HV on the electric plant itself wrong? Can it be that the analog output device DIRIS A41 scales the values itself and sends me engineering units instead of raw values?

AI table


I/O table for AI


HW Test

Well it looks like your IO link is fine. When you say power do you mean mA? Perhaps there is a termination issue?

In you AI Table, the AI column is where you would put your scaling for Engineering units (EU) right now they are scaled 0 to 100 with 20% Live Zero. That means if you look at this table online you will see the EU from 0 to 100 and it is set up fro 4-20mA or 1-4VDC. If you want the 0 to be zero you have to selet 20% Live Zero and make it 0 also. I would recomend if using the AI column for your EU to make the max number larger for more resolution.

I'll be online most of the day so if you have any more questions let me know.

LV and HV issue

Okay, the solution seems to be this -> LV and HV depends on the physical setup and an engineer has to play with LV and HV values until the right raw analog input (AI) appears on HW test of Moscad toolbox . Raw AI should be converted to engineering units (EGU) using the formula found at http://www.plcs.net/dcforum/DCForumID1/2755.html , the result should be very close to the actual results at the station. In my case real values could be found on the screens of Diris A41 devices.

So, I with the help of an engineer at the electric station itself we managed to guess that LV is -100 and HV is +300 for total active and reactive powers. (Note: You have to program it on Diris A41 as 100 and 300). Again, LV and HV could be very different depending on the physical setup at the given station.

And now finally the outcome of active and reactive power seems to be correct. Tomorrow we plan to go again and play with LV and HV for frequency and voltage .

MOSCAD is a quirky PLC for sure. But if it was easy then anyone could program it. Good luck and if there is anything else I can help you with let me know.

Webhead said:

MOSCAD is a quirky PLC for sure. But if it was easy then anyone could program it. Good luck and if there is anything else I can help you with let me know.

Click to expand...

Thx Webhead,
I feel really good after I have installed the system. However, I advise these things before trying PLC;

-be an Electrical & Electronics graduate
-go to training
-seek help from experienced PLC engineers

As a matter of fact the I got good analog outputs for voltage (LV=0 and HV=400) and frequency (LV=0 and HV=5000). It turns out that almost any LV and HV can be used at station, as long as the raw output values are within 800 and 2000 range.

this thread can be considered "closed"