View Full Version : Modbus communication to SVX9000 VFD's
November 20th, 2007, 05:47 PM
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
November 20th, 2007, 08:35 PM
Did you set parameters 852 to 859 to the numbers of the data you want to monitor?
November 21st, 2007, 11:22 AM
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?
November 21st, 2007, 11:34 AM
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.
November 21st, 2007, 11:43 AM
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.