S5 95U analog output value

Hello Everyone,

I am in the process of converting a S5 95U PLc to a S7 system. I need some clarification regarding the onboard analog outputs of S5. I am using one analog output and it is 0-20mA. When I monitor online in S5 I see that the QW value is ~5275 (decimal) and the current is ~6.xmA. But the manual says it is 1024 units. what is the maximum analog value that the S5 95U can process. I want to know this so that I can scale it accordingly to 27648 for the S7 system.

Thanks

Hi,

According to the documentation attached, there is a maximum range of 2046 units and not 1024.

Be careful, you have to use special bloc RLG.AA to extract value from the Analog word "Qw".

Regards.

Hello Prassanna;

The S7 analog input moduleshave their own logic that is different from their S5 equivalent(as you point out they will all use a numerical range 0-27648 or ±26748), and there are special functions (FC 105 "Scale" and FC 106 "Unscale") that are available in Step 7 to bring the analog values to (and from) engineering values.

I suggest you simply reprogram them directly in the S7 project, without attempting to convert them. You will save much time and energy that way.

See the following FAQ, for starters, and look at section 9.1 of the From S5 to S7 manual (on analog signal processing in the S7 PLCs):

How and for which analog measurements can you use the function FC105 'SCALE' to convert the integer values (INT) into real number values?

https://support.industry.siemens.com/cs/ww/en/view/1765297

This application example shows how to manipulate an analog input (from a pressure transmitter) and scale it usinmg FC 105. It might give you hints for your own project.

S7-300/400 CPUs: Pressure Measurement in the S7-CPU Using SITRANS P Transmitter

https://support.industry.siemens.com/cs/ww/en/view/23642357

Hope this helps,

Daniel Chartier

Panov69

Hi,

According to the documentation attached, there is a maximum range of 2046 units and not 1024.

Be careful, you have to use special bloc RLG.AA to extract value from the Analog word "Qw".

Regards.

 Hello 

sorry but our friend Prassanna speaks of Analog Output and not Input, if i read the manual for S5 Analog output OnBoard, Table 12-13 on page 12-10 i read 1024 and not 2048, there is an error? 

S5-90U/S5-95U Programmable Controller System Manual - Siemens 

New question published by MedRamy is split to a separate thread with the subject Analog output 4-20mA instead of 0-10v which is linked with the Pin14.

Best regards
Jen_Moderator