On Mon, 28 Jan 2008, Chris Morley wrote:
> Date: Mon, 28 Jan 2008 05:02:14 +0000
> From: Chris Morley <[EMAIL PROTECTED]>
> Reply-To: "Enhanced Machine Controller (EMC)"
> <[email protected]>
> To: "Enhanced Machine Controller (EMC)" <[email protected]>
> Subject: Re: [Emc-users] RFC, Modbus Spec.
>
>
> I would think a loadable config file would be nessasary as every device is
> different as far as how many, what type ,and what address of the
> device/data. That seems to be why MUDBUS was used so much - they didn't
> force much format to the data packets. If you had a loadable config file
> your module could load that file then make HAL pins to suit. Then you would
> only need one MODBUS module -it would just load different/more configs for
> different devices. Classicladder uses this type of idea. It has a config
> window that you set all this info and assign varriables to MODBUS addresses.
> You can set it to access data in multiple discontigous ranges. It is loaded
> when you load the ladder program.
>
> I am wondering what people are using to connect to their VDFs -MODBUS wise.
> I have a VDF that uses rs-485 or rs-422 but of course I only have a serial
> port. I have seen converters from serial port (rs-232) to rs-485. I've heard
> of USB to rs485. I did see that MESA makes a daughter board that plugs into
> the 5120 (which I use) that will produce rs-485. The problem with that is a
> driver needs to be written and worse, I lose alot of input/output.
We're doing some things that will alleviate the loss of I/O somewhat, a couple
of new daughter boards coming out in a few months. One, the 7I45 is a 8 axis
version of the 7I33, using only one FPGA connector. It saves pins by using
isolated SPI DACs. Also we have a 7I64 Isolated I/O card with 24 inputs and 24
outputs. This has three interface options, SPI from a 5I2X type FPGA card
(SPI Uses 10 pins total so 5 7I64s = 240 I/O points will connect to one FPGA
connector), RS-485 (up to 10 MBps) and USB.
Peter Wallace
Mesa Electronics
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