Modbus form Omron CP1E and a Danfoss drive

Hello!

I have tried to communicate with a Danfoss drive Aqua FC301 over RS485 but I had no sucess!

Attached you will find the demo project that I'm using. I want to read the register 2910 wich is B5F in HEX base minus one.

I have used the following registers:
d1300- node id - #0001

d1301- function code of read - #0003

d1302 - number of bytes to read - #0004 (Want to read two registers, each one has one word so I have 4 bytes to read the two registers: status word and main actual value)

d1303 - address of register to read - 1 - #0B5F

d1304 - Number of address to read - #0002 (Want to read 2 registers: status word and main actual value)

d1305 - CRC - #4A2D

To calculate the CRC I have used the following link:
https://www.lammertbies.nl/comm/info/crc-calculation.html

I have put all the zeros to calculate the CRC, since I have seen that if I do not put them the number is different.

Can anyone point to me where is the problem?

Thanks,
Bruno

https://www.myomron.com/index.php?action=kb&article=1243

Here is some information and sample program on the Omron website. The CRC calculations are automatic when selecting the Modbus protocol for the communication device.

Hope this helps you out.
Regards,

Hello Gclshortt!

I have already gone throw the examples that you have pointed out on your link but still no sucess!

I have hardwire the omron cp1w-cif11 in the following way:
All dip switchs ON expect number except numer 4.

- Terminal 68 from Danfoss connected to RDB+ and SDB+ pins
- Terminal 69 from Danfoss connected to RDB- and SDB- pins

Another thing that perhaps could make the diference is that this optional board is connected on the right port of the CP1E PLC. The system bits for starting RS485 are still the same?

https://www.myomron.com/index.php?action=kb&article=1257

The position of the optional board will make a difference. See the above link.

Regards,

Hmm, I'm a little confused now! lol

Looking at the table on the last link, I can see some system bits for serial communication on RS232. Correct? Or this are the bits that I have to use also for RS485?

In that case, wich bit substitute for A640.0/A640.1/A640.2?

Thanks for the help. It's my first time that I work on a project with Modbus!

If you only have 1 device, then checkout the EasyModbus download over at MrPLC by PMCR, it has examples on all required steps.

http://forums.mrplc.com/index.php?/...-modbus-rtu-master-for-cp1l-cp1h-cj1-cj2-cs1/

First (this is of no consequense for your question), the FC301 is an Automation Drive and the FC202 is the Aqua drive ;-)

0x0B5F is 2911, I think it should be 2909 (0xB5D) instead.

Does the PLC add 40000 hex to the Holding register by itself? Otherwise this might be a try as well.