I/O Configuration on a PLC connected to Anybus Gateway (slave)

Hi,

I am using a Anybus Profibus-Serial gateway to interface my device (RS 232 based) with a Profibus network.

I have configured the gateway so that any data change on the first four bytes of the Out area in the gateway generate a command to my device.

My application needs all the 4 bytes together to execute a command, can the PLC update all 4 bytes in one shot ??

If the PLC updates the bytes one by one, then the gateway would execute the command 4 times.

I hope the above problem is clear enough...

thanks
a

On the Siemens S7 PLC side, the I/O via DP is updated all at the same time if the S7 user program loads or transfers the data as a 4-byte address.

For example

L PID300 // loads 4 bytes 300-303 from the peripherial inputs.
T "Some_DWORD".

L "Another_DWORD"
T PQD300 // transfers 4 bytes 300-303 to the peripherial outputs.

Notice that if more than 4 bytes must be transferred consistently (i.e. in one block together) the S7 user program has to use SFC14 and SFC15 instead of simple load/transfer instructions.

Thanks for the reply...

I think the gateway will generate a single command as the address update would be very fast by PLC.

thanks
a