Re: [CAD_CAM_EDM_DRO] Interface options, headless boxen, and remote control ...

Bryan-TheBS-Smith wrote:

>
> IEEE 1284 / Bi-directional Parallel
>
> Be it your typical BiDi parallel or full-up IEEE 1284, I feel that
> parallel ports are more "standard" than USB when it comes to
> software -- and can be just as fast or faster. With 8 parallel data
> lines, it is just about as close to a GPIO (general purpose I/O) bus
> as you can get without building a prototype board with a
> microcontroller driving it. Unfortunately, not all microcontrollers
> are designed to handle parallel I/O -- which make mean it is not
> ideal for most application-specific devices. Worse yet, while extra
> parallel ports can be installed and well supported via ISA cards,
> PCI-based parallel port cards are usually non-standard and Windows
> 9x/ME only (NT/2000 drivers if you are lucky). And like
> MIDI/Gameport, I'm afraid that it too will becomes less common as
> USB gains ground.

I have developed a line of boards that connect to the parallel port,
using the hardware handshaking part of the 1284 protocol. The software
protocol required for automatic recognition of units on the bus was
not used, as there is no CPU on these units. (They run a lot faster
without software overhead.) See http://pico-systems.com/PPMC.html
for some info on what is completed already. I have a backplane that
is mostly a multitap extension of the parallel port. This transfers data
at about 800 KBYTES per second.

> IEEE 488 / GPIB (General Purpose Interface-I/O Bus)
>
> My understanding of GPIB is strictly from a "user" standpoint. Must
> of the lab and scientific work I have done has usually been by using
> a PC connected to various equipment via GPIB (with a GPIB controller
> in a PC). So I'm totally ignorant when it comes to being
> knowledgable about how GPIB works. What I "assume" is that GPIB is
> more than just an interface, but more of a networking interconnect
> between systems (with GPIB able to control 8-32 systems?, using a
> "double-sided connector" at the host?). As such, I "assume" it is
> not for driving and controlling "dumb" components but complete,
> "intelligent" systems. In such cases, Ethernet could serve the same
> purpose and is outside of the interest of CNC-EMC (except for
> connecting to the EMC system itself -- more below).

I've used this at work for some equipment, and it is quite slow. About
the equivalent of 10 to 25 Kbytes/second compared to using the parallel
port. It takes handshaking 3 bytes across the bus to send one 8-bit
byte of binary data as a decimal ASCII number.

Jon