Siemens Assistance


Thread Starter

Warren Boswell

I am currently working on a project to upgrade CO2 driers from an old Siemens S5-90u to a centralized Yokogawa Centum DCS system. I've never worked with Siemens S5 before, so some of the questions I'll be asking are likely to seem rather stupid to some of the wizards here, but without any manuals or documentation and only a hardcopy of the STL and CSF, I've hit quite a few snags...

First question:

When defining the time constant for a timer eg: KT 180.2, what is the format for the constant. Is the first part the time constant and the second the time base? If so, what are the time base definitions?

Like I said, pretty dumb question, I know, but any help would be greatly appreciated.

Many Thanks,

Hello Warren;

When first dealing with S5 PLCs, remember they are more than 20 years old, and initial programming was not even DOS... Limitations in available memory and graphic environments make for a very different machine than the newer processors. There are packages available to program them in a Windows environment (search for "S5 for WINDOWS" among others) but the Step 5 software from Siemens can be pretty daunting at first.

First, a link to the system manual for the manual:

It covers hardware (CPU and module) programming in Step 5 and instruction lists.

Now, for your question:
The L KT 180.2 (load timer constant) is pretty much as you described it.
L --> load operation (used in Structured Text only)
KT--> Timer constant
180-> time value (BCD, limited from 0 to 999)
.2--> time base code

The time base can be:
0 : 0.01s
1 : 0.1s
2 : 1s
3 : 10s

You will find much more insformation in the suggested manual, in the section of Step 5 operations.

Hope this helps,
Daniel Chartier

The answer to your question is yes, the format is as you described. The time base code is as follows:

0 = 0.01 second
1 = 0.1 second
2 = 1 second
3 = 10 second

The following link will get you a manual which I hope will help you with your endeavor.

Thank you,

David Adams
Application Engineer
[email protected]
334-567-2017 office
334-567-8614 fax
334-303-9499 cell