Remote IO Help

[BobO]

No. EDRV100 only talks to a single drive.

[ATU]

Why arn't the multi-drop communications implemented?  Seems like a natural configuration.

[BobO]

As a simple Modbus device, sure, and the gateway does exactly that. As the drive adapter, it reports as an EBC, and although it could support multiple devices, it isn't nearly as easy to implement, and 485 network congestion becomes a real problem at the slow baud rates used.

But compared to the price of the motor and drive, is it really that big a deal?

[ATU]

Depends on the application, it could be. The GS4 drives have the Modbus $80 option card. Compared to the GS-EDRV100 $200 solution. Most of the machines of any size that I have worked on in the last 10 years have all been some form of Ethernet I/O, If I had a slew of motor drives scattered all over a warehouse or assembly line, more than likely there is going to be Ethernet all over the place. That's why I chose the GS4 drives, because it had that option. If I was trying to reduce cost (like most OEM's)  and save the $80 and more if I went to a less capable drive, especially on large installations, I would use the 485 multi-drop if I was only changing speeds occasionally, simple start stops and monitoring.
s

[BobO]

We've talked about both multi-drop and/or cost reducing, it just hasn't been a super high priority. Significantly simpler programming with the EDRV100, but it isn't difficult with Modbus.

[Garyhlucas]

In our industry spares have to be factored into the cost analysis.  So that is why I try to stay with a single architecture so that spare parts are common everywhere.  Even did this with AB. PLC with no I/O and Point Block I/O both local and remote.

With our product we probably won't go to actual remote I/O because we are trying to keep our master code base completely common to all projects.  So anything custom to a particular job that must be added goes in its own PLC.  We use the same PLC for that even if it costs more, because we get to reduce our spare budget.

[franji1]

Why arn't the multi-drop communications implemented?  Seems like a natural configuration.

The MB-GATEWAY does exactly that.  However, it's just Modbus/TCP, NOT Do-more's native "Ethernet I/O".  You have to do all the polling via your own MRX/MWX of the relevant drive parameters, along with handling of drives going "offline".

GSEDRV100 takes care of all of that (but only one per drive).  That is the trade-off.

[Controls Guy]

Cheaper, but basically no benefit other than performance. You'll be using MRX/MWX just like you would through the 485 port. With the EDRV100, it's supported through the Ethernet I/O master. All of the relevant make-it-go registers are mapped to a structure, and the GSREGRD/WR instructions make register access painless.

And now that we've got UDT's (user types, not date/time), you should be able to create one for the drive data map and overlay it over the Modbus registers, so it's just about as cool as using the EDRV.

[ATU]

And now that we've got UDT's (user types, not date/time), you should be able to create one for the drive data map and overlay it over the Modbus registers, so it's just about as cool as using the EDRV.

Great Idea!