innoaloe

CP1E MODBUS Maximum Slave

9 posts in this topic

Hello everyone,

so I noticed in Omron's CP1E manual, there are no certain info on maximum number of Modbus Slaves that can be attached, however the PLC itself able to connect to slave number 1 - 247

I have read from common MODBUS specs, that 32 slaves are the limit for most MODBUS connections. However there are also statements that with proper design (1/8 transceivers) that we can extend number of connected slaves to 256. Anyone have experience or info about this with Omron PLC?

Thanks in advance

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Bump!!!

Anyone? :D

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Checking the manual, it says: Slave address (00 to F7 hex).  I have constructed Modbus networks before with more than 32 nodes, but I have never checked it out with CP1E.  Perhaps PMCR will comment.

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Thank you Jay.

Yes indeed the manual state so. But I'm comparing it to the SCU41-V1 manual which clearly states only 32 slaves able to be connected.
So I'm not really sure CP1E can do more than 32 @_@

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Innoaloe .

 

You need a reapeter so you can add next 32 slaves .

 

 

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2 hours ago, Johanb said:

Innoaloe .

 

You need a reapeter so you can add next 32 slaves .

Hello Johan, thanks for replying. Well... whether to add repeater or not I think depends on the network load and distance right? My main concern is actually whether the PLC can address slaves whose unit number is more than 32...

So far haven't got any exact answer for this, but as Jay said before, he can do more than 32 slaves.

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Innoaloe .

Our company adress over 32 slave numbers keeping in mind that the max length of comunincation cable is 100 mtr .

or no more then 32 Slaves .

the total lenght is the som off all the cable between master to slave and slave to slave .

I am trying to have a CJ2M OMRON PLC to communicate with a Danfoss FC51 using a SCU42 .

And so far no luck .

do you have a example prog I may try ?

 

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9 hours ago, Johanb said:

Innoaloe .

Our company adress over 32 slave numbers keeping in mind that the max length of comunincation cable is 100 mtr .

or no more then 32 Slaves .

the total lenght is the som off all the cable between master to slave and slave to slave .

I am trying to have a CJ2M OMRON PLC to communicate with a Danfoss FC51 using a SCU42 .

And so far no luck .

do you have a example prog I may try ?

Hello Johanb,

regarding cable length then the max actual device distance from the master should be 50 meters, I pressume?

Regarding Danfoss modbus, I haven't tried to use this device before for modbus, but any modbus slave should have the same configs. If you are using latest version of SCU42, you can use the Serial Gateway mode to enter the Modbus commands directly to the PLC memory. For sample program you can refer to https://www.myomron.com/index.php?action=kb&article=577  which contains samples for Modbus-RTU using Protocol Macro.

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Thanks Innoaloe .

 

I will try your suggestions .

 

 

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