Special Memory S7 1200

Hello

One more quick question. I am using FB to program my PLC. On the first FB "EN" pin on the left hand side of the FBD I currently have a switch wired in with a constant logic 1 so that the FB's in series are Enabled.

is there any way of specify a logic 1 constantly instead of having to wire a 1 signal. I have tried typing "True" on the EN but the plc wont accept it. From using a S7 200 I remember there was a contact called "SM" something that always closed when the PLC was put into run mode. I cannot remember the exact address if anyone can tell me it would be useful

thanks

Check the hardware properties of the CPU and enable the system bits and clock, you get to set the address of the always on and off bits as well as the clock byte.

On the S7-200 you had to have a contact before instructions with an enable input, you don't need that with the S7-1200. Connect the enable directly to the left hand supply bar. If you do need 'always on' or special timer bits like the S7-200 had then as Mike_RH go in to 'Device Configuration' and set some M memory to be used for System and Clock memory.

I am actually using Function block Programming (to try it out and i think it suits my program better) therefore there is no left hand supply bar (as far as i can see). I am not using Ladder programming so i dont believe i have a left hand side bar

hello [email protected],

the always ON memory bit in s7200 is SM0.0, and first scan cycle ON SM0.1...

here a link from siemens on how to do it:

https://www.automation.siemens.com/WW/forum/guests/PostShow.aspx?HTTPS=REDIR&PageIndex=1&PostID=197651&Language=en

I am kind of old fashioned and never got round to that new fangled Function Block Diagram stuff. As Mike_RH said, go in to the properties for the PLC and enable System and Clock memory, you will get a bit just like SM0.0 only you get to choose the memory addresses to use.

Yep got that problem sorted last week. program is working fine only for the performance of the HSC. Still working on trying to improve the measurment

thanks