Siemens S7-300 & Micromaster 440

I am trying, for the first time, to write values to the control word of a Micromaster 440 using an S7-300 PLC. I barely know what I'm doing, and what I'm doing isn't working.

I am using the MOVE command to move MW20 to PQW256, and am flipping M 21.3 via a button on the HMI to start and stop the drive. It ain't working.

It looks to me like bit 3 of the control word "enables" and "disables" operation, so if I byte swap MW20, that makes bit 3 of the control word M21.3.

I can at least see that I am successfully flipping M21.3 in a watch table.

Have any of you guys ever done this before? Is it obvious what I'm doing wrong? Perhaps I'm doing EVERYTHING wrong?

Have you followed some guide for setting up the MM4 drive to accept commands via Profibus ? And for setting up Profibus network with the PLC as DP master and the MM4 as DP slave ?

I really suggest that you connect your PC to the MM4 and use the STARTER software to monitor.
With the STARTER software you can follow the command path live. So you can see if the start command enters the drive, or if the drive is waiting for the start command from another source because of some parameters.
There are several ways to connect STARTER to the MM4. If the controlling S7 PLC has ethernet onboard, you can use routing so you go via Ethernet from your PC to the drive on Profibus. This bit may take a bit of advice to get going though.

If the Ethernet to Profibus routing is too big a mouthful at the moment, you can use a simple BOP panel on the MM4 to investigate the bits in the control word. And then you can work yourself backwards through the parameters that decide how the control word is supplied with commands. Takes some patience but is doable.

JesperMP said:

If the Ethernet to Profibus routing is too big a mouthful at the moment, you can use a simple BOP panel on the MM4 to investigate the bits in the control word. And then you can work yourself backwards through the parameters that decide how the control word is supplied with commands. Takes some patience but is doable.

Click to expand...

Many thanks for the tips, Jesper. Sadly, it looks like there is simply too much I do not know how to do. I don't have the prerequisite knowledge to accomplish the task.

Thanks again for taking the time to read and reply.

Hi!


Google MM440 PLIST to find the parameter list.

Check the setting of ... was it P3 = 3 (?) to get access.

To enable control via profibus, set P700/INDEX 0 to 6.

To enable setpoint via profibus, set P1000/INDEX 0 to 6.



Look at the status word and assign symbolic names to your M-bits (or DBX-bits).

Do the same with the control word and your bits in MW20.

Now you should be able to play with the bits and to watch the response.

Edit: The speed setpoint is in the output word next to the control word. 4000H = 60 Hz (it refers to the setting in P2000).
The actual speed is in the input word next to the status word.



Kalle