S7-400 and Step7

danielcarter · Jul 22, 2006

Good day everyone! Im looking for some help with regards to the Siemens S7-400 PLC. Im a student working on a tech thesis which envolves a conveyor and robotic arm assembly. My problem is that I have the plc wired and powered up and all the hardware configured to what i think is right. Im trying to test a few components with a simple program consisting of a limit switch and solenoid. when I download the program to the plc and switch it to run mode and activate the limit switch noting happens in the step 7 program(the state of the limit switch does not change)in monitor mode and the solenoid valve does not activate. but the bit led on the card turns on (input card) nothing happens to the bit light on the output card. any ideas to what may be causing this??? I need help!

rsdoran · Jul 22, 2006

A suggestion, get something like http://www.pdf995.com/ which will allow you to "print" a report of the Ladder or whatever program convention you are using.

You can then upload that pdf so ALL may see how you have written the program. This offers the most options for assistance.

If you can not figure out how to do that then post your Simatic S7 file, in a zip file, and those with the appropriate software may be able to assist.

marinko · Jul 22, 2006

It must work

Check adresses in symbol table. Maybe limit switch or solenoid valve have wrong adresses.

danielcarter · Jul 22, 2006

Im using adresses I0.0 and Q0.0, the limit switch is wired into bit0 of the input card and the solenoid is wired into bit 0 of the out put card, my rack consists of slot 1,2 Power supply, 3 CPU, 4 CP, 5 DI ac input card, 6 DO ac output card, 7 DI 24vdc input card, 8 DO 24vdc output card, im wondering if there is somethinf wrong with the addressing but i dont know what to try

marinko · Jul 22, 2006

Daniel,

I 0.0 and Q 0.0 are wrong adresses.
Open Simatic Manager, click your simatic station. On the right pane are appeared two icons: Hardware and yours CPU. Double click hardware and hardware configuration for yours project will open. If it was configurated before you will see detailed I/O configuration with adresses. If not, you must specify which cards are put in the slots, in the same way as they're physically connected (i.e. slots 1 and 2 power supply, slot 3 CPU ...).

danielcarter · Jul 22, 2006

I have done this and have gone through the entire setup of the system but thhes are the addresses that are automaticlly placed in the hardware config table. it displays 0...2 for DI 120v and 0...2 for the DO 120v modules??? Gotta love Siemens hey! haha

moggie · Jul 23, 2006

If you are sure that the I/O is configured/connected correct then it must be your program?

Where have you written your code?
Is it in an FC or FB?
If it is then you will have to "call" this FC/FB from OB1.

If you can post your code thenwe will be able to help more.

PLucas · Jul 23, 2006

Daniel

I assume that you only monitored the single bit address I0.0 when you checked your program and within the program block, be that OB1 or an FC ETC, there is the possibility that you have not wired the limit switch into I0.0, only what you think is I0.0. Open up a VAT and insert all the address's of the I/O avalable and monitor what input is activating in there.

If you are unsure how to insert a VAT and use that for monitoring I/O then say so and one of us will guide you through the process.

It might also be useful if you can archive your entire project and post it here, then those of us with Simatic Mangler can have a look, just in case you have the hardware setup incorrect.

Paul

PeterW · Jul 23, 2006

You can monitor the I/O card direct from Hardware Profile, try doing this for you input card and see if any inputs are coming on at all. This would be the software equivalent of seing the led come on.

Any hardware related errors, red lights etc, look at your hardware profile on-line an see if any errors highlight.

re-download your hardware into the cpu.

ivo.maenen · Jul 23, 2006

Maybe section 'A8' and others from this link can help you;

http://www.automation.siemens.com/fea/html_76/down_module.htm

danielcarter · Jul 23, 2006

Hey guys, I have tried looking at the I/O table of the input card that i have my limit switchs fed to, there are three bit lights active and no change in the any of the address's in the table, Im stumped on what todo... I have attached a few screen shots for you to look at and see if you can maybe see something im doing wrong..

THANKS !

PeterW · Jul 23, 2006

Turn on the outputs, Q 0.1 to Q 5.7, you can switch them on via a VAT table or from the modify function in your second screen dump, by selecting an output card.

It all looks OK.

Do you have any diagnostic errors?

also in the hardware profile, try going online. thats the button 3rd from left on top, between the open file icon and the ssve icon.

danielcarter · Jul 23, 2006

I just tried the oline button and it says everything is ok, but the adress tables are still not changing state when there bit is activated. how do i open a VAT table?

danielcarter · Jul 23, 2006

Oh and there are no errors on any of the cards and the consistancy check is all ok!

PeterW · Jul 23, 2006

How to create a VAT table.

Go to the project block section, where OB1 is, right click and insert a new object, the choices will be Org block, function, function block, data block, variablr table and udt.

select variable table, once created open it.

In the left hand column enter qw0 and below that qd2, both in word format.

click on-line (by poking the eyes), then in the right hand column you can enter a value. w#16#ffff for example, as the outputs are not programmed, they should stay on.

S7-400 and Step7

danielcarter

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rsdoran

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marinko

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danielcarter

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marinko

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danielcarter

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moggie

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PLucas

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PeterW

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ivo.maenen

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danielcarter

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PeterW

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