Hello,

I have several drives connected from an AC450 to a NDBU-95C via AF100 through a CI810b, and some others drives are connected as well in the same AF100 bus, but instead of using the NDBU, these drives uses individual CI810b Field card interface.

So, in the same AF100 bus, outside the NDBU, there are some DC500 drives with their individual CI810b to communicate over the SDCS CON 2 board.
I would like to insert all of DCS500 drives in the NDBU-95c to remove the Ci810 in each drive (and the tap AF100 cable from the bus), and use only one CI810 BEFORE the NDBU-95c.

As i saw in DCS500 documentation, it is represented as NDBU-85 link to DCS500, but I supose it is due the old version documentation, and communicstion via NDBU 95 is also possible in newer systems.
I know about the optical limitations in 5Mbd and 10Megabaud transmitting speef for equipment, and it can not be mixed, but my topology is not star (up to 12 drives), instead it is point to point from the NDBU (9 drives), so I am not mixing 5 with 10mbd equipment, and we have as well RDCO-03c (5mbd) communicating with NDBU-95c so it should not be a limitation on this type of topology. In other words, NDBU95 is able to communicate with 5Mbd equipment, but it is not clearly mentioned.

I dont know how to handle this communication. According to DCS500 documentation, it is a Fieldbus communication, and should be done with AC70 or FCI in CON-2, not being neccesary the COM-5 (Which are also available on our drives, but not used, just CMT PC Tool purposes).

Do you know if there is some limitation which i am not attending?
ABB documentation says plastic fiber to control should not exceed 20m (DCS500), and also NDBU is set to long distance (cable is about 30m).
30m is accepted on NDBU documentation.


In Advant Controller 450 DRIENG Element, the status is HW Missing, but I configured the slave address just one address increased the previous drive.
Parameters in DCS500 are set to:

1212 (node 23, node in plc 107). This is 1*16+7 as specified in other nodes.

4001 : 2 = Advant / DDCS


Taken from the DCS600 documentation, slave address in drive is position (in drieng) *16 + units, so this seems to be correct.

I didnt see any confguration related to communication speed in any parameter of DCS500.

I tried to be as clearly as I could, but if you have any question or i havent mentioned something, please let me know


Can anyone help me?
I have the original CD rom with so many documentation if neccesary.

Thank you!!

 

DCS to Modbus communication issues are often caused by timing and configuration mismatches.

Things to check:
- Response timeout on the DCS side - Modbus devices can be slow, especially over serial. Try increasing the timeout to 2-3 seconds.
- Polling rate - too fast can overwhelm the slave device. Start at 1-2 second intervals.
- RS-485 wiring - proper termination (120 ohm at each end), correct A/B polarity
- Slave ID conflicts - each device on the bus must have a unique ID (1-247)

For pre-commissioning testing, I simulate the Modbus devices on a PC using ModbusSimulator (modbussimulator.com). You can set up multiple slave instances matching your field device register maps and test the DCS polling configuration before any hardware is installed. Saves a lot of time during commissioning.