Controller Interfaces

[John O]

I'm digging through the manuals of several of the major integrated
controllers, such as AMX, Crestron, Ocelot, Homevision, and the like. Why do
these guys use an RS-232 computer interface as the primary connection, as
opposed to USB, or something a bit newer? AMX makes a $4000 controller,
which uses a 30-year-old comm method. Why?

-John O

[Dave Houston]

"John O" <johno@#no^spam&heathkit.com> wrote:

>I'm digging through the manuals of several of the major integrated
>controllers, such as AMX, Crestron, Ocelot, Homevision, and the like. Why do
>these guys use an RS-232 computer interface as the primary connection, as
>opposed to USB, or something a bit newer? AMX makes a $4000 controller,
>which uses a 30-year-old comm method. Why?

It's cheap, simple, reliable, well understood, and can be used at distances
far greater than is possible with USB. On the manufacturing side, USB adds
more cost than RS-232.

Also, most of those you list were designed before USB became ubiquitous.

[Si Ballenger]

On Wed, 02 Mar 2005 22:05:26 GMT, nobody@whocares.com (Dave
Houston) wrote:

>"John O" <johno@#no^spam&heathkit.com> wrote:
>
>>I'm digging through the manuals of several of the major integrated
>>controllers, such as AMX, Crestron, Ocelot, Homevision, and the like. Why do
>>these guys use an RS-232 computer interface as the primary connection, as
>>opposed to USB, or something a bit newer? AMX makes a $4000 controller,
>>which uses a 30-year-old comm method. Why?
>
>It's cheap, simple, reliable, well understood, and can be used at distances
>far greater than is possible with USB. On the manufacturing side, USB adds
>more cost than RS-232.
>
>Also, most of those you list were designed before USB became ubiquitous.

And you can buy a decent USB to serial adapter for $12.

[John O]

>
>>I'm digging through the manuals of several of the major integrated
>>controllers, such as AMX, Crestron, Ocelot, Homevision, and the like. Why
>>do
>>these guys use an RS-232 computer interface as the primary connection, as
>>opposed to USB, or something a bit newer? AMX makes a $4000 controller,
>>which uses a 30-year-old comm method. Why?
>
> It's cheap, simple, reliable, well understood, and can be used at
> distances
> far greater than is possible with USB. On the manufacturing side, USB adds
> more cost than RS-232.

Do all these guys use the same RS-232 implementation? I recall in the
mid-80's when RS-232 as a standard was nearly meaningless...DTE, DCE, 9-pin,
25-pin, and even then some big-company engineers re-arranged it so it was
'better.' I built a lot of cables by hand after reading the pinouts, in
those days.

A side question...other then a PC for config, what other device would be
attached to the serial ports? Do standard cables work for these, or do most
installers have to build them...because they'll both be DCE or something?
And now I'm thinking...you probably build these every time because of the
distance and route of the cable, which makes the RS-232 pinout issue a key
skill.


Last Q for now: What is ICSNet? Is this something AMX developed? (my web
searching is turning up zeros and lots of AMX-related hits)

Thanks!

-John O

[Dave Houston]

"John O" <johno@#no^spam&heathkit.com> wrote:

>>
>>>I'm digging through the manuals of several of the major integrated
>>>controllers, such as AMX, Crestron, Ocelot, Homevision, and the like. Why
>>>do
>>>these guys use an RS-232 computer interface as the primary connection, as
>>>opposed to USB, or something a bit newer? AMX makes a $4000 controller,
>>>which uses a 30-year-old comm method. Why?
>>
>> It's cheap, simple, reliable, well understood, and can be used at
>> distances
>> far greater than is possible with USB. On the manufacturing side, USB adds
>> more cost than RS-232.
>
>Do all these guys use the same RS-232 implementation? I recall in the
>mid-80's when RS-232 as a standard was nearly meaningless...DTE, DCE, 9-pin,
>25-pin, and even then some big-company engineers re-arranged it so it was
>'better.' I built a lot of cables by hand after reading the pinouts, in
>those days.
>
>A side question...other then a PC for config, what other device would be
>attached to the serial ports? Do standard cables work for these, or do most
>installers have to build them...because they'll both be DCE or something?
>And now I'm thinking...you probably build these every time because of the
>distance and route of the cable, which makes the RS-232 pinout issue a key
>skill.
>
>
>Last Q for now: What is ICSNet? Is this something AMX developed? (my web
>searching is turning up zeros and lots of AMX-related hits)
>
>Thanks!
>
>-John O
>

While I'm not intimately familiar with each piece of gear listed, my guess
is they all use extremely simplified versions of RS-232. The Ocelot/Leopard
uses only 3 wires (RD, TD, & GND) and I suspect most of those you list do
the same as the embedded microcontrollers they use have a limited number of
pins. Some may also work on 0-5V levels rather than the defined RS-232
voltage levels. Many PCs (especially laptops) also use 0-5V levels on their
RS-232 ports. The lower voltages reduce the effective cable length.

The ones I'm familiar with expect to connect to a PC so a standard cable
will work. Some may require a null cable but I would expect that to be
spelled out in the documentation.

I've never heard of ICSNet. Maybe someone else can help with it. There are
several proprietary systems based on RS-485, CAN, etc.

[John O]

>
> While I'm not intimately familiar with each piece of gear listed, my guess
> is they all use extremely simplified versions of RS-232. The
> Ocelot/Leopard
> uses only 3 wires (RD, TD, & GND) and I suspect most of those you list do
> the same as the embedded microcontrollers they use have a limited number
> of
> pins. Some may also work on 0-5V levels rather than the defined RS-232
> voltage levels. Many PCs (especially laptops) also use 0-5V levels on
> their
> RS-232 ports. The lower voltages reduce the effective cable length.
>
> The ones I'm familiar with expect to connect to a PC so a standard cable
> will work. Some may require a null cable but I would expect that to be
> spelled out in the documentation.

LOL, when I mentioned people messing up the "standard" I forgot about the
voltages. Looks like Homevision has a USB, but you have to do serial first
to get it set up.


> I've never heard of ICSNet. Maybe someone else can help with it. There are
> several proprietary systems based on RS-485, CAN, etc.

I know that it involves a proprietary protocol, and AMX claims it is for
1000-foot control of all sorts of devices, I'm beginning to suspect it is
their own special network.

Thanks for your help, Dave.

-John O

[Rod Speed]

John O <johno@#no^spam&heathkit.com> wrote in message
news:EfqVd.5309$DW.3352@newssvr17.news.prodigy.com ...

> I'm digging through the manuals of several of the major integrated
> controllers, such as AMX, Crestron, Ocelot, Homevision, and the like. Why do
> these guys use an RS-232 computer interface as the primary connection, as
> opposed to USB, or something a bit newer? AMX makes a $4000 controller, which
> uses a 30-year-old comm method. Why?

Usual reason, it takes time for stuff like USB to take over.

Its not surprising that it happens sooner with mice and modems etc.

[Rod Speed]

John O <johno@#no^spam&heathkit.com> wrote in message
news:1OFVd.39020$by5.7723@newssvr19.news.prodigy.c om...

>>> I'm digging through the manuals of several of the major integrated
>>> controllers, such as AMX, Crestron, Ocelot, Homevision, and the like. Why do
>>> these guys use an RS-232 computer interface as the primary connection, as
>>> opposed to USB, or something a bit newer? AMX makes a $4000 controller,
>>> which uses a 30-year-old comm method. Why?

>> It's cheap, simple, reliable, well understood, and can be used at distances
>> far greater than is possible with USB.

10/100 Cat 5 makes a lot more sense if you need the distance.

>> On the manufacturing side, USB adds more cost than RS-232.

Not really. Have a look at the cost of USB mice now.

> Do all these guys use the same RS-232 implementation?

Near enough basically.

> I recall in the mid-80's when RS-232 as a standard was nearly
> meaningless...DTE, DCE, 9-pin, 25-pin,

It wasnt quite that bad.

> and even then some big-company engineers re-arranged it so it was 'better.' I
> built a lot of cables by hand after reading the pinouts, in those days.

Yeah, but its not so bad now.

> A side question...other then a PC for config, what other device would be
> attached to the serial ports?

Just other less common stuff now, like
radios, smart card programmers etc.

> Do standard cables work for these,

Usually. Not so much with radios tho.

> or do most installers have to build them...
> because they'll both be DCE or something?

Nope, just use what is supplied.

> And now I'm thinking...you probably build these every time because of the
> distance and route of the cable,

Nope, they're usually located near the PC controlling them.

> which makes the RS-232 pinout issue a key skill.

Not anymore.

[John O]

Thanks Rod, I appreciate your thoughts.

"Rod Speed" <rod_speed@yahoo.com> wrote in message
news:38pp7qF5mp3q2U1@individual.net...
>
> John O <johno@#no^spam&heathkit.com> wrote in message
> news:1OFVd.39020$by5.7723@newssvr19.news.prodigy.c om...
>
>>>> I'm digging through the manuals of several of the major integrated
>>>> controllers, such as AMX, Crestron, Ocelot, Homevision, and the like.
>>>> Why do these guys use an RS-232 computer interface as the primary
>>>> connection, as opposed to USB, or something a bit newer? AMX makes a
>>>> $4000 controller, which uses a 30-year-old comm method. Why?
>
>>> It's cheap, simple, reliable, well understood, and can be used at
>>> distances far greater than is possible with USB.
>
> 10/100 Cat 5 makes a lot more sense if you need the distance.
>
>>> On the manufacturing side, USB adds more cost than RS-232.
>
> Not really. Have a look at the cost of USB mice now.
>
>> Do all these guys use the same RS-232 implementation?
>
> Near enough basically.
>
>> I recall in the mid-80's when RS-232 as a standard was nearly
>> meaningless...DTE, DCE, 9-pin, 25-pin,
>
> It wasnt quite that bad.
>
>> and even then some big-company engineers re-arranged it so it was
>> 'better.' I built a lot of cables by hand after reading the pinouts, in
>> those days.
>
> Yeah, but its not so bad now.
>
>> A side question...other then a PC for config, what other device would be
>> attached to the serial ports?
>
> Just other less common stuff now, like
> radios, smart card programmers etc.
>
>> Do standard cables work for these,
>
> Usually. Not so much with radios tho.
>
>> or do most installers have to build them...
>> because they'll both be DCE or something?
>
> Nope, just use what is supplied.
>
>> And now I'm thinking...you probably build these every time because of the
>> distance and route of the cable,
>
> Nope, they're usually located near the PC controlling them.
>
>> which makes the RS-232 pinout issue a key skill.
>
> Not anymore.
>
>