Read Torque Value From S120

Folks, I have an 840D sl system with various S120 drives. I would like to read out the torque and speed of these drives to a SCADA system via the X130 interface of the 840D. I do not have an OPC license for it nor are the plans to get one at the moment, so next idea is to get the data in to the CPU where I can get at it via S7-Communication.

Here's where I'm at. 840D CPU/S120 are configured with a free telegram to get the torque/speed over to the CPU side. The torque value I am using is from r80[1]. As it is a float32 data type, it is spanning two words on the telegram. I know the S120 swaps the words (big endian?) so the CPU is swapping the words in the double word. Side note, the speed value works fine.

Now, there is -a- value coming over however it is not anywhere near what is displayed in Starter for the torque when the motor is running. Like, off by a factor of +/- 1,000,000,000. I'm thinking there's some sort of scaling or other conversion somewhere? Or I'm doing something else wrong. If I open Starter communication and live view the CPU data side by side, it -looks- like the same hex data is making it across though it is hard to see as it updates at different rates.

Question being, am I on the right track? Is there another conversion I need to make somewhere?

Easy / standard solution is something like this:

Configure telegram communications for drive object(s)

Select Telegram 352 if your particular drive allows that using starter.

352 includes scaled motor current and motor torque as well as fault and warning codes, plus motor speed and status word.

It's a quite useful telegram for non-motion controlled drives.

The way the motor current / torque / speed works for that telegram:

It sends a scaled value, +/-16384 represents +/- relative to reference speed, current, and torque.

Reference and max are not required to be the same values, but they should be at least as big as the large possible value they could ever see.

For example, max rpm might be 4000, but reference speed might be 4500 or 5000 rpm.  This would allow capturing how far above max rpm the motor went after it faulted.

In the PLC, norm_x and scale_x the returned value to get into engineering units. 

For current, let's say reference Amps = 1000. Set 0 to +16384 for the NORM_X min/max. Output of NORM_X goes to input of SCALE_X, with min=0.0, max = 100.0 (as REAL)

That gives you motor current with ~~ +/- 6mA resolution in the case of a 100A reference amps value. For reference amps of 1000A, it's +/- 60mA.

Same process for torque and speed (and voltage if you want it).

I think most people create an FB to perform drive parameter scaling, or do it in SCL in a single telegram 352 FB.  FYI, Siemens offers a ready-made Telegram_352 FB in the Sinamics library in TIA Portal V15+.

dnaines

Folks, I have an 840D sl system with various S120 drives. I would like to read out the torque and speed of these drives to a SCADA system via the X130 interface of the 840D. I do not have an OPC license for it nor are the plans to get one at the moment, so next idea is to get the data in to the CPU where I can get at it via S7-Communication.

Here's where I'm at. 840D CPU/S120 are configured with a free telegram to get the torque/speed over to the CPU side. The torque value I am using is from r80[1]. As it is a float32 data type, it is spanning two words on the telegram. I know the S120 swaps the words (big endian?) so the CPU is swapping the words in the double word. Side note, the speed value works fine.

Now, there is -a- value coming over however it is not anywhere near what is displayed in Starter for the torque when the motor is running. Like, off by a factor of +/- 1,000,000,000. I'm thinking there's some sort of scaling or other conversion somewhere? Or I'm doing something else wrong. If I open Starter communication and live view the CPU data side by side, it -looks- like the same hex data is making it across though it is hard to see as it updates at different rates.

Question being, am I on the right track? Is there another conversion I need to make somewhere?

Aha! So I am missing a conversion. In my continued research, I have come across an S120 Function Manual and in said manual it states that r0080 is data type is actually a 16bit integer rather than the float32 that is mentioned in the help file of Starter on the same parameter (I'd assume it actually means the int16 is meant to be converted to float), so I believe I am mucking it up pulling it over from the drive as a double word.

As for the telegram, I'm not going to mess with the current setup as it was a pre-me installation and it is set up with a free telegram that doesn't quite match the RX/TX status bit wise of a standard telegram and would be a pain to track down all the usage in the program to change it (maybe on a rainy day). I just extended the address range and tacked the torque on the end. (side gripe, the DB that the SINA_FB is writing to was initially created using the standard UDTs, but at some point in time the telegram was switched to free and modified but the UDB/DB never updated.. so that was fun!)

For the conversion. The value I see in p2003 is 575.01 (no idea the rhyme or reason, that is just what is currently in there). I'm using S7 manager V5, so no SCL unfortunately! 

So I'd normalize to 0 to 16384 as you said then scale that to 0.0 to 575.01? I'll have to try it out next week.

Thanks for the help!

Hi,

yes to normalize calculate:

value = received value / 16384 * 575.01

(best is to convert the numbers to REAL data type before)

e.g.

value = 8192.0 / 16384.0 * 575.01 = 287,505

expressed in hex the received value corresponds to:

4000hex = 100%

7FFFhex = 199,99%

FFFFhex = -200%

I am using Simatic Manager V5.5, which does not have blocks for normalizing and scaling like Tia Portal (though I did see there were libraries that could be downloaded). I just did the math longways as my values were simple enough.

As Robert said, the value first needs to be converted to real. Starting value is Int, so use I_DI block to go from Int to DInt then DI_R block to go from DInt to Real.

For normalizing, the formula is NormalizedValue = (RawRealValue - NormMin) / (NormMax - NormMin). My min values are zero, so simplified to RawRealValue / NormMax (NormMax being 16384). Using block MUL_R for this. Again, if any of the values are not expressed in a real data type, the block will not work.

If someone knows of a document describing the reasoning behind the 16384, I'd be interested!

For scaling the formula is ScaledValue = NormalizedValue * ((ScaleHigh - ScaleLow) + ScaleLow). Again, scale low is always zero, so simplified to NormalizedValue * ScaleHigh. The scale high value is the reference value in parameter P200X (whichever one is being converted).

Even after the conversions, the values were still pretty noisy. I am using the smoothed parameters however p0045 was defaulted to 1mS.. changing to 100mS to match what the displayed values are smoothed to helped a bit.

To answer your question:

 https://support.industry.siemens.com/tf//WW/en/posts/why-we-use-4000-hex-in-scaling/230809

How I got the link?  Online search: 

"site:siemens.com sinamics 16#4000 why" 

and it was the first link.

0_Einstein

To answer your question:

 https://support.industry.siemens.com/tf//WW/en/posts/why-we-use-4000-hex-in-scaling/230809

How I got the link?  Online search: 

"site:siemens.com sinamics 16#4000 why" 

and it was the first link.

 Thanks! I was searching the 16384 :/ so close