Siemens s7-300....first scan...and communication error......

Hello, i need some help with siemens s7-300. I want you to tell me how i can set some initial values in the first scan of the program!also how can i run a block every 1 hour for example. In Hitachi plcs this was done with some special bits...but in siemens how its done? At last i would like to set an alarm when a communication error is occured, i have search and found that OB87 is doing this. is this right? how i can program it?

thank you a lot

Hi,

the OB100 (hot restart) , OB101 (Re-start) and OB102 (cold restart) can help you... they are called depending on the startup mode.

To run a block every minute, hour, day, etc.. you can use the OB10 to OB17...

For you alarm, you can do for instance, in OB87 :

SET
S "myDB".myAlarm

Hope it helps...
bye

Hi

All brand PLC will spoon feed you but Siemens does not.
You can see:http://www.plctalk.net/qanda/showthread.php?t=34415 and several others.

You can set a output in OB 87 and then when communication failure does occur it can sound an alarm or light a LED up!
Ex:
AN Q0.0
SET Q0.0

thank you for your time.....i will try it and tell you if it is all ok thanks again

pascal22 said:

...the OB100 (hot restart) , OB101 (Re-start) and OB102 (cold restart) can help you... they are called depending on the startup mode.

Click to expand...

Not quite....he's using a S7-300, so only OB100 Warm Restart (and OB102 Cold Restart if the CPU is a 318-2) is available.

pascal22 said:

For you alarm, you can do for instance, in OB87 :

SET
S "myDB".myAlarm

Click to expand...

Is there any simple way to RESET it again, after communication error is removed?

I mean, it has no "ongoing" and "outgoing" property like OB81 has, has it?

supec said:

Is there any simple way to RESET it again, after communication error is removed?

Click to expand...

OB 87 is called on each event.......

An event is error coming as well as error going......

Means within the data supplied by OB 87 you'll be able to know if it's coming or going.
The rest is cake....

I'm not sure what You mean...
How can I differentiate between "incoming" and "outgoing" event?

For OB81 it is OB81_EV_CLASS = B#16#39 for incoming and B#16#38 for outgoing. But OB87 has B#16#35 only.

Can You post some example for OB87?

Jeebs said:

Means within the data supplied by OB 87 you'll be able to know if it's coming or going.

Click to expand...

How? Top. Sorry, but I need to know!

Look at the temp area of the OB.

Also this manual lists standard functions and OB's.

http://support.automation.siemens.com/WW/llisapi.dll?func=cslib.csinfo〈=en&siteid=cseus&aktprim=0&extranet=standard&viewreg=WW&objid=10805383&treeLang=en

System Software for S7-300/400 System and Standard Functions

OB87 TEMP area

Sorry,but I cannot see,which byte I should use in case of OB87!
Please, can You tell me?

OB87_EV_CLASS BYTE Event class and identifiers: B#16#35
OB87_FLT_ID BYTE Error codepossible values: B#16#D2, B#16#D3, B#16#D4, B#16#D5, B#16#E1, B#16#E2, B#16#E3, B#16#E4, B#16#E5, B#16#E6)
OB87_PRIORITY BYTE · Priority class; can be assigned via STEP 7 (hardware configuration)
OB87_OB_NUMBR BYTE OB number (87)
OB87_RESERVED_1 BYTE Reserved
OB87_RESERVED_2 BYTE Reserved
OB87_RESERVED_3 WORD Depends on the error code
OB87_RESERVED_4 DWORD Depends on the error code
OB87_DATE_TIME DATE_AND_TIME DATE_AND_TIME of day when the OB was called

If you have that manual I poted, the fault ID is explained in the OB87 section and towards the end of the manual there is a description of event codes.

Still cannot see it

Do You mean the table below (page 63 of proposed SFX_e.pdf)? I cannot see any "outgoing" message there...

Error code Byte/Word Meaning
· B#16#D2:· B#16#D3· B#16#D4:· B#16#D5 OB87_RESERVED_3:· OB87_RESERVED_4: Transmission of diagnostic entries currently not possible.Synchronization messages cannot be transmitted (master).Illegal time-of-day jump due to clock synchronization.Error when receiving synchronization time (slave).Contains no further information.Contains no further information.
· B#16#E1:· B#16#E3:· B#16#E4: OB87_RESERVED_3: OB87_RESERVED_4: High byte:Low byte: Incorrect frame ID during global data communication.Frame length error during global data communication.Illegal GD packet number received.interface ID (0: K bus, 1: MPI)GD circuit numberContains no further information.
· B#16#E2: OB87_RESERVED_3: OB87_RESERVED_4: High word:Low word: GD packet status cannot be entered in the DBDB numberContains no further information.· GD circle number (high byte),· GD packet number (low byte)
· B#16#E5:
OB87_RESERVED_3: OB87_RESERVED_4:
High word:
Low word: Access error to DB during data exchange via communication function blocksReserved for internal use by CPU.Number of block containing the MC7 command that caused the error.Relative address of the MC7 command that has caused the error.

Amongst other things the event code tells wehether its an incoming (going into fault) or outgoing (coming out of fault) call.