MicroMaster 420 and 440 to run off HMI through S7-1500

 Hi,

I have made some assumptions here, as your MM420 wiring for example states terminal 5 and 8 are wired, then this must mean your PLC start output is driving an interposing relay, otherwise you would have wired terminal 9 (or terminal 28 for the MM440) as the 0V reference

Also, assume that you have run through some sort of commissioning of the motor data.

As you have only one input to run the drive, all other run/inhibit signals must be forced to logic '1'

Digitals:

P840 can be set to r722.0 (to react to terminal 5)

P844 = P845 = P848 = P849 = 1

P731 = r52.2 (Drive running feedback)

Analogs: (As the MM420 does not have a current ADC, you will need to wire a 500ohm resistor across terminals 3 & 4)

P1000 = 2 (to read the analogue input)

P756 = 0

P757 = 2 (2V is equivalent to 4mA)

P2000 = 50/60Hz depends on what the motor plate states

The analogs for the MM440 are slightly different

P756 = 2 (Don't forget to check the DIP switch for ADC1 is set to ON to read 0-20mA)

P757 = 4 (raise the lower threshold for the current to 4mA)

Hope this helps a little.

Regards,

Graeme

Hi, sounds like the start command is not being recognised at the digital input, do you have a sketch of the wiring, as I suspect there is a referencing issue.

You can view the digital inputs on the BOP, by looking at r722, if you cannot see bit 0 toggling when you start and stop, then there is a hardware issue.

If there is no relay between the PLC and the drive, and you are using the PLC 24V to drive the digital input, then the drive requires a 0VDC reference from the PLC as well.

See the block diagrams attached, note, there are wiring differences between the MM420 and MM440, so be careful.

Regards,

Graeme

Hi, with the drive stopped, when you press the start button on the HMI, can you please look at the following parameters on the BOP and send a picture of each as they may look a bit strange to you?

r52 & r54

Regards,

Graeme