S7-1200 1214C outputs

Good afternoon forum,

Im programming a S7-1200 1214C DC/DC/DC and i need outputs that send negative.

My question is, can i change the +24v for the -24v in the 3L+ 3M for example :

3L+: -24v      3M: +24v

Thank you in advance

Hello Jackcaress,

Please have a look at the following links:

What is the meaning of the terms "sinking" (German: "P-schaltend") and "sourcing" (German: "M-schaltend") in digital modules of SIMATIC?

And in Appendix A of the manual:

SIMATIC S7 S7-1200 Programmable controller

It is not possible with the outputs.

Best regards,

Wizard

Jackcaress

Good afternoon forum,

Im programming a S7-1200 1214C DC/DC/DC and i need outputs that send negative.

My question is, can i change the +24v for the -24v in the 3L+ 3M for example :

3L+: -24v      3M: +24v

Thank you in advance

 Hello,

If you did that, then the voltage difference between 3L+ & 3M will be 48VDC which will damage your CPU.

If you want to connect negative voltage, it means connecting -24VDC to 3L+ & 0VDC to 3M.

I am not very much sure that it will work. As normally the voltage connected to +3L pin is used to power the transistors inside the CPU. And it should not be less than the voltage connected to 3M.

To solve your problem, I do recommend to use external relays.

Hope this helps.

Ayman Elotaify

 

Jackcaress

Good afternoon forum,

Im programming a S7-1200 1214C DC/DC/DC and i need outputs that send negative.

My question is, can i change the +24v for the -24v in the 3L+ 3M for example :

3L+: -24v      3M: +24v

Thank you in advance

 Hello,

If you did that, then the voltage difference between 3L+ & 3M will be 48VDC which will damage your CPU.

If you want to connect negative voltage, it means connecting -24VDC to 3L+ & 0VDC to 3M.

I am not very much sure that it will work. As normally the voltage connected to +3L pin is used to power the transistors inside the CPU. And it should not be less than the voltage connected to 3M.

To solve your problem, I do recommend to use external relays.

Hope this helps.

 The power supply was taken from the s71200, how could it be 48v?

So to connect it in a way where it sends negative i need -24v from the power supply and 0v from ground?   i had it connected the ``wrong´´ way around for a while +3l -24v  3m +24v,

i hope i havent damged it

Jackcaress

 

Ayman Elotaify

 

Jackcaress

Good afternoon forum,

Im programming a S7-1200 1214C DC/DC/DC and i need outputs that send negative.

My question is, can i change the +24v for the -24v in the 3L+ 3M for example :

3L+: -24v      3M: +24v

Thank you in advance

 Hello,

If you did that, then the voltage difference between 3L+ & 3M will be 48VDC which will damage your CPU.

If you want to connect negative voltage, it means connecting -24VDC to 3L+ & 0VDC to 3M.

I am not very much sure that it will work. As normally the voltage connected to +3L pin is used to power the transistors inside the CPU. And it should not be less than the voltage connected to 3M.

To solve your problem, I do recommend to use external relays.

Hope this helps.

 The power supply was taken from the s71200, how could it be 48v?

So to connect it in a way where it sends negative i need -24v from the power supply and 0v from ground?   i had it connected the ``wrong´´ way around for a while +3l -24v  3m +24v,

i hope i havent damged it

 Ok.

I told that the voltage difference between 3L+ & 3M will reach to 48VDC based on your statemnet that you will connect -24VDC to 3L+ & +24VDC to 3M.

Which means that voltage difference = +24 - (-24) = 48VDC.

_________

If you are using Siemens Power Supply with Output 24VDC, and you connected the +24 VDC to 3M pin and connect +24VDC to +3L pin, I don't think that it will be power the transistor circuits inside the CPU.

Don't consider it as auxilary contacts of relays.

You can use external relay as I told you in my previous post and it should work.

Hope this helps.

I have cables everywere but it works 

Cheers guys