I am new user of Siemens s7-200 (Cpu212)PLCs. I want to write tachometer program in Siemens,up to some point I have achieved to do so. But at high speeds I can not read the signal from motor shaft. One of my friend said to me that I should use high speed counters. However,I have tried to use through wizard but I couldn't. So I need a program that really show how I can use HSC properly. Another problem, if it is possible to use one input of PLC (ex. I0.0) as an input interrupt, instead of input interrupt counter. Thanks for your concern. my e-mail: [email protected], you can send program to my e-mail.

 

If you use the Microwin Programming Software you can click (left?, right?) the special instructuion (HSC? or so) in the instructions tree. An assistant pops up and let's you select a counter, define mode and parameters for it's operation.
HTH

 

1. You can download "tips and tricks" from siemens website www4.ad.siemens.de. You will see HSC examples there. These examples also exist in S7-200 Documentation CD. If you are writing from Turkey, you can find Turkish manual of S7-200 from website www.siemens.com.tr/s7200. This manual includes some HSC examples also.

2. Altough in S7-200 manual it is mentioned that you should not use an interrupt input for two different purposes, we assigned 2 interrupts (one HSC, one rising edge) to a single input and it seems to work properly. However, when you look at PLC Information tab, you see a non-fatal error. It is possible that some interrupts cannot be caught in this application. Try it at your own risk.

 

This is the old series of the s7-200 plc but i believe the program at http://www.germainesystems.co.uk/tacho_demo.pdf will still work. The input i0.0 should manage 20khz Early series one CPUs had some anomalies in the firmware Mainly to do with analogue processing, although who knows, if you can elaborate on the problem I may be able to help.

marc sinclair