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Speed Selection

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#1 electron

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Posted 12 June 2012 - 09:48 PM

Hello Omron Modbus Gurus,

i'm on the way to selecting drive inverter directly or using communication

ussually we drivin inverter direct thru analog output, but using analog for controlling a mass of inverter (around 18) will take high cost,
while using communication offering lower cost and lot of usefull status

now since more fast communication become possible, this thought emerge again, would control from modbus (protocol macro using SCU31) fast enough compared to direct analog control ?

best regards for your experience and knowledges sight

#2 PMCR

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Posted 17 June 2012 - 10:37 AM

Hello electron


The answer to your question depends partly on what you consider 'fast enough'.

Here are my thoughts:


1. You will get the best performance if you split the comms between the 2 ports on an SCU31, putting 9 inverters on 1 port, and 9 on port 2.


2. You will be able to read the status of all the inverters approximately every 2 seconds.

3. The way that I do Modbus and inverter speed changes involves a ladder stack, where I push frequency changes as well as start / stop commands onto a stack, and then service the stack when the port is available. You can get several commands per second out to your inverters, but if you are looking to change speed on each inverter every 1/2 second, Modbus is probably not the best way to go.

#3 electron

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Posted 29 June 2012 - 07:55 PM

Hi PMCR,

Thank you for the thought,
from your experience i made conclusion, that highspeed speed control still can't use communication for now

Best Regards,

Hello electron


The answer to your question depends partly on what you consider 'fast enough'.

Here are my thoughts:

1. You will get the best performance if you split the comms between the 2 ports on an SCU31, putting 9 inverters on 1 port, and 9 on port 2.


2. You will be able to read the status of all the inverters approximately every 2 seconds.

3. The way that I do Modbus and inverter speed changes involves a ladder stack, where I push frequency changes as well as start / stop commands onto a stack, and then service the stack when the port is available. You can get several commands per second out to your inverters, but if you are looking to change speed on each inverter every 1/2 second, Modbus is probably not the best way to go.






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