Modbus communication to SVX9000 VFD's

[mdwyer39]

Hi, I'm trying to communicate between a SCADAPack and three Cutler Hammer SVX9000 VFD's. The VFD's have an expander card that allows me to communicate RS-485. I have been able to write to the VFD. I can start/stop it and send speed setpoints. However I do not get any status back.

Just wondering if anyone has had this problem. I am trying to read back the registers specified by the manaul but I still don't get anything back.

Any comments is greatly appreciated

[ndzied1]

Did you set parameters 852 to 859 to the numbers of the data you want to monitor?

[mdwyer39]

Yes I have. From the Modus & N2 Communication Kit User module for the expander card it specifies the parameters and registers as:
ID Modbus Register Name
2101 42101 FB Status Word
2102 42102 FB General Status Word
2103 42103 FB Actual Speed
2104 42104 FB Process Data Out1
.
.
2111 42111 FB Process Data Out8

I have set parameters
852 to 2101
853 to 2102
854 to 2103

But I still don't get anything. Do you know what registers are for parameters 852...859? Would they be 40852 to 40859?

[SLC_Integrator]

In the Scadapack are you getting any MSTR block errors?

Be aware that in Scadpack only one MSTR block can be active at any given time, not 4 at a time like in 984LL.
If the blocks are all happy and your just getting zeroes back then it must be a drive side issue.

[mdwyer39]

No I do not get any MSTR block errors. And only one MSTR block is active at any given time. I agree it seems like it is on the drive side.