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CX-Protcol MODBUS Serial Communication

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#1 Jojo712

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Posted 04 April 2012 - 08:14 AM

Hello All,
I am trying to connect 2 Schneider variable speed drives to an OMRON CS1W-SCU31-V1 using CX-Protocol. I also have in this communication circuit 16 OMRON E5CN Temperature controllers. I can already communicate with the OMRON Temperature controllers but have no luck/success with the Schneider VSD's.

The protocols I am using now was taken from the ModbusPM Protocol Macro. I used this PM before on another project to coomunicate with Hellas Rectifiers and I was able to communicate these rectifiers with no problem in communication just some setting/config issues on the Hellas rectifiers.

My plan was to use Port 1 of the SCU31 for the temperature controllers and then Port 2 for the VSD's. I have tried communicating with the temperature controllers on both Port 1 and Port 2 and did not encounter any communication issue. I can send the setpoint value to the Temperature controllers and I can see the changes on the units. however when I tried again to connect the VSD's on any of the 2 ports I have no response from the VSD's.

I have the tech gusys from Schneider double checked my settings for the VSD communication and all communication setting parameters are correct. I also connect the VSD's to the ModScan software using the same junction box and cable that I am using to connect to the CS1W-SCU31 and I am always able to connect to the VSD via the ModScan software. I can change the reference frequency thru the software and can see the change in the VSD's.

Is there any other cases or issues like this with CX-Protocol or CS1W-SCU31? I think my biggest problem is that I don't get any error message from the CX-Protocol or CS1W-SCU31, so I can't figure out where or what to do next.

Any comment/help will be highly appreciated.

Many Thanks in Advance
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#2 ejn99

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Posted 04 April 2012 - 10:02 AM

Hi

I have been experimenting with ModbusPM Protocol Macro. The Read_03 ladder of the Master_sample has a problem in the error routine. My conclusion is that
the correct field to be used is 'Sequence Abort Completion Flag' - (1509.10 for unit 0). I don't know if this observation is of any help.

I'd be glad if someone will confirm this.

Regards - Edmund
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#3 lostcontrol

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Posted 04 April 2012 - 01:57 PM

Hello All,
I am trying to connect 2 Schneider variable speed drives to an OMRON CS1W-SCU31-V1 using CX-Protocol. I also have in this communication circuit 16 OMRON E5CN Temperature controllers. I can already communicate with the OMRON Temperature controllers but have no luck/success with the Schneider VSD's.

What version Schneider drives are you using?

I have the tech gusys from Schneider double checked my settings for the VSD communication and all communication setting parameters are correct. I also connect the VSD's to the ModScan software using the same junction box and cable that I am using to connect to the CS1W-SCU31 and I am always able to connect to the VSD via the ModScan software. I can change the reference frequency thru the software and can see the change in the VSD's.

Is your cable from the SCU correct? Have you tried running Modscan the other way, to see what the SCU is sending out the Serial Port you wish to use?

Is there any other cases or issues like this with CX-Protocol or CS1W-SCU31? I think my biggest problem is that I don't get any error message from the CX-Protocol or CS1W-SCU31, so I can't figure out where or what to do next.

Start by using the Trace tool in CX-Protocol, this is very useful for diagnosing what is happening, if indeed the correct message format is being transmitted & if there is any response at all

#4 BobB

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Posted 04 April 2012 - 03:57 PM

Another thing you should watch with Schneider - if you choose 8, 1, none it will not usually work. You need to select 8, 2, none.
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#5 Jojo712

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Posted 04 April 2012 - 08:51 PM


Hello All,
I am trying to connect 2 Schneider variable speed drives to an OMRON CS1W-SCU31-V1 using CX-Protocol. I also have in this communication circuit 16 OMRON E5CN Temperature controllers. I can already communicate with the OMRON Temperature controllers but have no luck/success with the Schneider VSD's.

What version Schneider drives are you using?

I have the tech gusys from Schneider double checked my settings for the VSD communication and all communication setting parameters are correct. I also connect the VSD's to the ModScan software using the same junction box and cable that I am using to connect to the CS1W-SCU31 and I am always able to connect to the VSD via the ModScan software. I can change the reference frequency thru the software and can see the change in the VSD's.

Is your cable from the SCU correct? Have you tried running Modscan the other way, to see what the SCU is sending out the Serial Port you wish to use?

Is there any other cases or issues like this with CX-Protocol or CS1W-SCU31? I think my biggest problem is that I don't get any error message from the CX-Protocol or CS1W-SCU31, so I can't figure out where or what to do next.

Start by using the Trace tool in CX-Protocol, this is very useful for diagnosing what is happening, if indeed the correct message format is being transmitted & if there is any response at all


I have not tried yet the reverse way, I thought the ModScan can only act as MODBUS Master. I will definitely try this setup also and will also use the Trace Tool.

Thanks a lot for the advice.

#6 Jojo712

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Posted 04 April 2012 - 09:17 PM

Another thing you should watch with Schneider - if you choose 8, 1, none it will not usually work. You need to select 8, 2, none.

I am currently using the MODBUS setting:
Baud rate = 9600
Comm parameters = 8 bits, Even parity, 1 stop bit.

One thing I found odd is that the Schneider communication manual states that the VSD reference frequency address is 8502, but if I am using the ModScan I must use the address 8503 in order to change the speed.

Anyway, I tried both addresses 8502 and 8503 but I still got no response from the VSD.

#7 BobB

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Posted 04 April 2012 - 09:22 PM

One thing I found odd is that the Schneider communication manual states that the VSD reference frequency address is 8502, but if I am using the ModScan I must use the address 8503 in order to change the speed.

1 to the right, 1 to the left - not uncommon.
You will usually find when reading from devices you have to read the 'real' address and not the 'Modbus' address. This is normally 1 address to the left.
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#8 Jojo712

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Posted 09 April 2012 - 10:22 PM



Hello All,
I am trying to connect 2 Schneider variable speed drives to an OMRON CS1W-SCU31-V1 using CX-Protocol. I also have in this communication circuit 16 OMRON E5CN Temperature controllers. I can already communicate with the OMRON Temperature controllers but have no luck/success with the Schneider VSD's.

What version Schneider drives are you using?

I have the tech gusys from Schneider double checked my settings for the VSD communication and all communication setting parameters are correct. I also connect the VSD's to the ModScan software using the same junction box and cable that I am using to connect to the CS1W-SCU31 and I am always able to connect to the VSD via the ModScan software. I can change the reference frequency thru the software and can see the change in the VSD's.

Is your cable from the SCU correct? Have you tried running Modscan the other way, to see what the SCU is sending out the Serial Port you wish to use?

Is there any other cases or issues like this with CX-Protocol or CS1W-SCU31? I think my biggest problem is that I don't get any error message from the CX-Protocol or CS1W-SCU31, so I can't figure out where or what to do next.

Start by using the Trace tool in CX-Protocol, this is very useful for diagnosing what is happening, if indeed the correct message format is being transmitted & if there is any response at all


I have not tried yet the reverse way, I thought the ModScan can only act as MODBUS Master. I will definitely try this setup also and will also use the Trace Tool.

Thanks a lot for the advice.


It seems the MODBUS software that I have now (ModScan) can only run as Master, it always need a device address in order to communicate.
As for the Trace tool, I was not able to activate it yet. Even if I am connected to the PLC through the SCU the command is always grayed out.
By the way the model of the Schneider VSD is ATV312H037N4.
Thanks.

#9 lostcontrol

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Posted 10 April 2012 - 04:47 AM

Search downloads for Multiway, this can be a master or slave.

The trace should work, I can't give an example just yet as am not in front of PC

#10 Jojo712

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Posted 10 April 2012 - 06:32 AM

Search downloads for Multiway, this can be a master or slave.

The trace should work, I can't give an example just yet as am not in front of PC


Yes, the trace works. I was able to see the data that was sent and data is in corrrect MODBUS format.
Send message [33] slave address in hex; [10] MODBUS write instruction; [85] [03] data address (Schneider defined addreess); [00] [01] one word; [02] two bytes; [nn] [nn] data ivalue in HEX; <C> check code.
Recieve message is just the same data (loop back data). I think there should be another data for the ACK reply from the slave.

The message data format I used for the VSD is the same message data format I am using for the temperature controllers.

I'll search for Multiway.

Thanks.

#11 BobB

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Posted 10 April 2012 - 03:29 PM

Here is a link to Multiway for you
http://forums.mrplc....ds&showfile=836
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#12 Jojo712

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Posted 10 April 2012 - 11:10 PM

Here is a link to Multiway for you
http://forums.mrplc....ds&showfile=836

Hello Bob,
Thanks for the link. I have already downloaded the Multiway softaware from an OMRON Europe site. It's a great tool and was very helpful to analyze the problem.
Thanks again for info about the Multiway software, it's a cliche but I wish would have known and used this tool before it could have saved me from a lot of headache like this.

#13 Jojo712

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Posted 10 April 2012 - 11:38 PM

Hello Guys,
Thanks a lot for the all the information specifically for the Trace Tool in the CX-Protocol and the Multiway Software (by the way, is this an official OMRON software?). I was able to see what's happening and found out my mistakes.
Just want to share the things that I learned from this experience:
1. Data address is not correct.
- I have used the address 8503 in the CX-Protocol transmission because it's the address that works for the ModScan software. CX-Protocol and Multiway both use the address 8502.
2. Data address must be in HEX format
- I have tried using the HEX format before but I was using the address 8503 and convert it to 2137H so there's also no response from the VSD when I was using he Multiway software. When I used the address 2136H (8502) then I was able to set the frequency reference of the VSD.

3. RS-485 port of the CS1W-SCU31-V1 is reverse polarity of the RS-485 port of the PC/Notebook serial COM
- In short if I can communicate with the device through Multiway or ModScan using exactly the same cable I used for the CX-Protocol/SCU31 then the cable is not correct for the CS1W-SCU31. Even the label of the adapters indicate that pin 1 is A+ and pin 2 is B- but for CS1W-SCU31, pin 1 is negative and pin 2 is positive.

Now I can finally communicate with the VSD by CX-Protocol (using MODBUS format) through the CS1W-SCU31 but when I tried to connect to either ModScan and Multiway using the same cable then I get no response.

It's most probably the same reason why I can't communicate with the Hellas rectifiers on my previous project using HELLAS configuration software but then I was able to connect with the rectifiers using the CJ1W-SCU31 and protocol macro. On that project, I ended up doing all the rectifier settings using protocol macro instead of the HELLAS configuration software. At least now I now that the RS232 to RS485 converter that I bought before (on that project) is working because I was able to use the same converter in this project. I thought it's because of this converter that's why I was not able to communicate with rectifiers.

Thank you all again for sharing your time and information.

#14 BobB

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Posted 10 April 2012 - 11:57 PM

Omron RS485 has always been pin 1 - and pin 2 +.
The addressing is also correct - Modscan and Modbus registers are always one to the right of the direct address.
I guess I am pretty used to using Modbus now and always automatically look one to the left.
Yes the address must be in HEX - that information is in the manual for the CX-P file for reading Modbus RTU.
Glad you got sorted - comms are nearly always a bit of magic.
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