Lauer profibus display with Siemens CPU


Thread Starter


I have a CPU Siemens 315-2DP(315-2AG10-0AB0) and a display Lauer LCA320 with profibus.
I see the display in the Simatic's hardware configuration but de display red led (err) lights and the CPU memory doesn´t change when pressing the display keys.

Could anybody help me?

I have been said that the problem is in the CPU program.


Daniel Chartier

Hello, jlpacho;

If you see the display in HWConfig, it probably is set-up as a Profibus slave. There are different settiogs that must be checked, once you make sure that all harware connections are OK (wiring, terminations...).

First , the Profibus address of the display (and the master CPU) must be correct. You say the LEDs on the display are active; are the SF and BUSF LEDs of the CPU also active? If so, the display could be set to another address from that seen in HWConfig. Try to find out how the Profibus address is set on the display: it could be dipswitches, rotary switches, or software (then you need a configuration file and some sort of connection to the display to change its parameters).
Or you could change the Profibus address in HWConfig to match the one on the display, compile the HWConfig and download to the CPU. In any case, the configured address in Step7 must match the address setup in the display.

Next, check the I/O addresss selected for the display. In HWConfig, if you ckick on the icon of the display attached to the Profibus network, a lower window will open specifying I adresses and Q adresses assigned to the slave (display). The I addresses are used by the CPU to read from the display, and the Q addresses are used to write to the display. With that information, open a cross-reference window in Step7 and check wether these addresses are effectively used in the CPU to exchange data with the display. Use a VAT table to see if the internal memory locations change in the CPU when acting on the display keys. If there is a problem there, you will have to correct it--either changimg the I/O addresses of the display in HWConfig, or rewiring your program addresses.

Hope this helps,
Daniel Chartier
I recently had a profibus problem with this CPU also. I was directed to the Siemens PLC hotline and got an answer. Call 1 800 333 7421.

Best regards,
Don Hebert
I've solved my problem. I had to look for the correct combination (8 bytes input, 8 byte ouput) of sub-elements of the "Lauer Profibus" item in the simatic catalog.

The GSD file offers some elements to insert in the profibus object. I knew than y had to use 8 bytes for intputs and 8 bytes for outputs but there was some posibilities. I found the correct combination trying somte times. I woud like to know why i had to choose these elements.