[VFD Drive's - Modbus or Analog]

Hi All

So I'm doing a new project involving a V560 (looks good!) and 3 x SEW motor drives. The drives can be controlled by either Modbus RTU or analog control signals. In previous projects I have used the analog route for simplicity/robustness. Modbus offers some improved functionality.

Having spent a large amount of time looking at Modbus in the Visilogic help files, help from other forum members and the drive documentation, I am still leaning towards analog.

A basic Modbus implementation would involve 4 read/write parameters (registers 1-4) and 7 status reads (registers 5-11) (For each drive)

Example:

Request:

[01] Drive address[03] Command [00][05] Register start address [00][01] No. of registers [94][0B] Checksum

Reply:

[01] Drive address[03] Command [02]No. of data bytes[00][00] Data[b8][44] Checksum.

Is there a checksum function or must each string be pre conceived?

Looking at the examples I see plenty of unitronics - unitronics master/slave applications. How different is Unitronics - (Other Vendor)? Examples would be good.

Is it practical to suggest a standard format datatable and ladder structure so users can share datatables of various devices? This is sort of bordering on UDFB, but I didn't want to say that out loud!

Sorry- as you might tell I'm a bit of Newbie in this dept.

Thanks.

[Advanced Web Server]

It appears IT has blocked the port forwarding on our network. I am trying to work with them now to get it fixed...

You got to love IT departments!

[Copy Rows - Max?]

Hi.

I'm wandering what the maximum amount of rows is that you can copy from datatable to datatable? I was able to get 360 rows to copy, but it wasn't working consistently, dropped it back to 250 and it seems ok.

I see that read/write max is 128 in help file, but couldn't find any reference to copy max.

Thanks.

[HSC wont accept store.]

Hi Team

I have configured a high speed counter on a IO-DI8-RO8 connected to an EX-RC1.

The counter is incrementing as the flow meter pulses (which is very slow) If I try to store a zero value to the MI assigned to the flow meter, it holds the zero whilst the condition is forced, but then reverts back to the previous value as soon as it is released.

--[MB0]------STORE

0 to MI50

If I use a positive transition on MB0 I dont even see the zero.

I use a HSC on a different V350 and it works great in this way as a crude shaft encoder using a proxy sensor on a toothed pulley.

Thanks