S7-300 Trouble getting it to run mode

[minerman]

Hello,

I have my S7 PLC on my desk, it is the CPU only. Is it possible to get this thing to run my program without the associated IO attached? Right now it is forced into stop mode and I'm not sure why. The error info is a little confusing. Here is some of the errors that I'm getting from the module diagnostics:


Serial number: S C-C7UG46772012


Event 1 of 92: Event ID 16# 4563
STOP caused by I/O access error (OB not loaded or not possible, or no FRB)
FC number: 3
Module address: 16
Previous operating mode: RUN
Requested operating mode: STOP (internal)
Internal error, Incoming event
06:33:35.714 PM 01/02/1994
(Coding: 16# 4563 FF84 8C00 0101 0003 0010)


Event 2 of 92: Event ID 16# 2942
I/O access error, reading
P area, word access, Access address: 256
Requested OB: I/O access error OB (OB122)
OB not found, or disabled, or cannot be started in the in the current operating mode
External error, Incoming event
06:33:35.710 PM 01/02/1994
(Coding: 16# 2942 FE7A 0020 0100 0000 0000)

Edit: Also, I'm constantly having trouble accessing the module. It seems like I have to download the hardware config again and again, then I have to reset the ethernet node. I don't know if this is related to the errors or not.

 

[KalleOlsen]

See event 2, put in an empty OB122.a

Your CPU will limp heavily trying to access all the missing IO. The speed would increase if you remove the calls of the blocks that accesses the IO.

Kalle

 

[minerman]

Thanks. I'm trying this but now I can't download at all. Not sure what has changed.


Nevermind... its magically working again.

 

[Mike_RH]

Are you using Step 7 Professional?
If you do, perhaps you would be better off to use the PLCSIM for testing, instead of the CPU on your desk?

 

[minerman]

Yes, I am. I think I may try the plcsim later. Actually, my main goal right now is to establish communications and to get some experience with the actual PLC. Maybe in a couple days, I will put the PLC back in the cabinet once I gain some confidence. I want to be good to go before I go out to the field.