MM440 analog input not changing freq. of drive.

Hi all!

I'm having a bit of a weird problem at the moment, and i'm hoping that someone here could help me out a bit.

We are using a MM440 to control a microcut which is being used in our stephan cook-it machine.

The problem we are having, is that the changes made on the HMI regarding speed setpoint, is not changing the actual setpoint of the vfd. The mm440 is only running at the minimum freq. set at P1080. 

Usually the vfd is being controlled between 0-50Hz, but now we've had to set a temporary Hz on parameter P1080 just to get it going. 

The setpoint source is a 0-10v signal from the plc, into vfd input 3 and 4.  I've measured the 0-10V signal when changing the setpoint on the HMI, and the signal is correct from the PLC and also on the terminals of the VFD.

P0010 is set to 0
P1000 is set to 2
P1300 is set to 0 (should this maybe be set to 20?).
r1438, r0022, r0062 and r0066 shows no changes when changing the setpoint value on the HMI. 
P0700 is set to 2

DIPswitches 1 and 2 are both OFF.

I have not been able to check parameter r0752 as the kettle is in use, without the microcut connected. I will check this in a couple of hours, but since i'm measuring the correct ADC on the terminals of the VFD, i'm guessing that this is ok.

Sorry if this question has been posted before.

Look at r0752:0, this is close to the analogue input. This should reflect the 0/10 Volt input.

If this is not responding the analogue input may be damaged.

Move the analogue in put to AIN2, and check r0752:1, you can use this as the set point if AIN1 is defective.

High Voltage transients on the analogue inputs can damage this area, unusual but I have seen it happen.

Come back if I can help further.

Tractor

 Thanks for the reply.

Tractor

Look at r0752:0, this is close to the analogue input. This should reflect the 0/10 Volt input

I checked this parameter as soon as the machine was available. The readout of this parameter matched the measured voltage. 

I took a look in the parameter-list again, and found out that parameter P0719 was set to 0. I changed this to 2. 

After changing this parameter, the drive worked as expected. 
The only thing i don't understand, is that we used this machine last week, and everything worked fine then. So something weird has happened.

Only changes made to this vfd since then, is increasing the ramp-down time. 

P0719 should be set to 0.

There must be something else wrong here, but for now the machine is working?

I will have a think and come back....

I see.

Why should this parameter be set to 0, instead of 2? Could you explain further?

Yes, the machine is working for now.

We were a bit stumped by this parameter change aswell, but as long the operators can actually use the machine without using the BOP, there's no rush.

Hello,

parameter p719 should be set to 2, cmd = bico, setpoint = analog input, when you use analog input as source for for speed setpoint.

With regards

Reference: MICROMASTER 440 Parameter List.

https://cache.industry.siemens.com/dl/files/204/23708204/att_60463/v1/440_PLi_23708204_en_0106.pdf

I have attached the drawing for the analogue input, this may help but I believe it does not go far enough.

The 'Parameter List', link above; here some drawings, page 259, indicate the path of the analogue input, but tricky to follow the connections.

I would reset the drive back to default and start again, however not knowing the complexity of the machine setup that is easy for me to say.

It is working now, so you may opt to leave it, but something has been changed. It is unlikely that the drive has done this.

I will leave this to you to think about, but please come back if i can offer any further help.

  (Looking at P0719, the default value is 0 in the manual?)

Tractor

We were facing same problem after Terminal replacement in drive panel. On checking we also found that in P0719 it is selected 0 where as for AI set point it should be 2, but at the same time in 1070, it was 0755 means BICO was used for AI as well.

To run the drive, we changed minimum frequency to 26 Hz, in P1080, on further checking 0755 was not changing when 4-20 mA input to drive from PLC was being changed and it was constant at 4096.

Then we checked polarity and found it is reverse, when it was changed, problem got resolved.

So in 0719 it can be 0 or 2 for AI input, but in case of 0, you will have to configure BICO manually by entering source in P1070. 

Regards

Tarun

This post and conversation helped in trouble shooting drive problem of MM440.

Thanks

Tarun

Thankyou for the feedback

Tractor