Arnt Serial and Parallel ports a little outdated?

[White Rabbit]

Why is it that just about all mounts still use this antiquated system?

I'd like to hook my mount up to starry night,but I don't have a serial port on my laptop, and from what I read the dongle converters don't work that well.

Isnt it time this gear came out of the stone age, or is there a valid reason for this?

Thanks

[skwinty]

Hi WR
Yes, the rs232 variety of serial port and parallel ports are rather old.
The USB port are the latest in serialports.
I think the reason for equipment keeping the rs232 is to allow for easy custom cable manufacture. These plugs are easily soldered as compared to USB connectors. (IMO):thumbsup:

[AndrewJ]

Some do some dont. Just for basic scope control via planetariums, most USB to Serial converters shld work. I know Belkin brand units have a bad reputation with Meades, but thats mostly in download mode.



One thing i like is that you aren't as limited by distance,
and RS232 "just works", you dont need specialised drivers for each item.
Also, handling RS232 serial in the scope end is much simpler than handling USB,hence manufacturers just keep it simple
I dont know about the other scopes, but Meades all use Motorola 68HC
cpus. To go USB, they would have to redesign the whole setup and hence start running two streams of hardware/firmware, to keep backwards compatability.
Integrated Ethernet comms would probably be nicer than USB too

Andrew

[g__day]

I'd prefer TCP/IP over a LAN cable too - gets around distance, speed, packet handling - basically everything.

[White Rabbit]

All valid points, from the retailers point of view , but in this day in age where the standard for data comms is USB, for a company to turn around and say that "we are continuing to use outdated interfaces because it's easier for us" just isn't looking after your customer base, nor staying on top of the game/competitor. It puts the responsibility's back on the customer. Same with the "it just works", because if your gear doesn't "just work" with todays standards then you need to and make it work. Am I being a bit harsh? It could just be a that I'm ignorant of the real reasons.

At the end of the day they are designing equipment with out dated interfaces. If they provided the correct converter that works with there gear and helps the customer interface with modern equipment then they would be looking after us, even if they charged a little extra for the converter. However, as I see it buying a converter (serial/usb) is hit and miss affair and these things aren't that cheap that I want to go out and buy one only to find that it doesn't work and I'm unable to return because I've opened the packaging.

Try buying a laptop these days with a serial port on it.
I don't want to start a revolution here I just don't understand the use of serial in astro gear.

This is probably a bit OT for this forum so please move it on if need be Admin.

[White Rabbit]

I agree Lan would be a good idea, as you could then go wireless as well, that would be sweet. I'm surprised with all the tech people that are into this hobby no one has come up with a work around.

[AndrewJ]

Yep
Its not really the fault of the scope/any other manufacturers that companies flog USB to RS232 converters that don't do what they should.

Andrew

[ozstockman]

Hi,

For a serial port check http://www.aircables.net/products.html for their bluetooth to serial modules.

Their two modules:

1) AIRcable Serial3 (http://www.aircables.net/serial.html)
2)AIRcable Serial3X (http://www.aircables.net/serial3x.html)
will connect with any bluetooth enabled laptop, desktop or even handheld pc through a virtual serial port.

If your laptop does not have Bluetooth integrated you can always buy a usb bluetooth dongle for just $5 -20. I've got mine for $4 on ebay.

I am using AIRcable Serial3X (http://www.aircables.net/serial3x.html) and it works excellent with EQDIR interface(direct connection to EQ mount) or when it's connected to a SynScan remote control. It also has a built in rechargeable battery. That's the only difference between Serial 3X and Serial 3.

Sorry, cannot help with parallel connection. It seems that the only option here is to buy a PCMCIA to parallel card.

cheers,

Michael

[rogerg]

Personally I don't see RS232 as outdated, it's just a very basic form of communication. I think it's still appropriate in many situations. I see it as sort of the no-thrills guaranteed communication method for low-bandwidth requirements.

To me, USB seems as overkill for something like telescope communications where the data throughput is so low but the overhead higher to build and run USB.

Parallel on the other hand, I see no need to continue utilising. I figure it was designed for higher bandwidth communication and now there are better higher bandwidth communication methods. What new products available do support it? Other than ToUCam's I'm not aware of any. Sure modified ToUCam's do use Parallel, but they're modified by people however they're able, so it makes sense there (if you want USB, someone's going to need to modify it for USB .... ).

[gary]

The Keyspan USA-19HS USB Serial Adapter is highly recommended and we
have found it to be 100% reliable over a very large number of installations
and when used in conjunction with all known modern Windows variants,
Mac OS X and Linux.

A reliable USB Serial Adapter is a combination of good hardware and most importantly
a good software driver.

As you have noted, not all USB Serial Adapters are born equal, so to speak.
Whereas USB was optimized for bulk data transfers, most telescope control
applications are typified by transfers that require only a few bytes of data at a time.
Some of the USB Serial Adapters on the market seem to fail in handling these
small data transfers, possibly in neglecting to correctly flush buffers. The Keyspan
device handles small data transfers equally as well as bulk data transfers and
it is one reason it is so popular in other industries, such as PLC applications
in mining and the sort.

When one looks at the entire world of USB connect peripherals,
one of the reasons why any arbitrary device and its associated driver may
not work on any given Windows variant 'out of the box' is undoubtedly often
due to the complexities of what is know as the "Windows Driver Model" (WDM).
Most of us have been a situation on the Windows platform when we required
to download a driver update from a manufacturer's web site in order to get
a USB peripheral to operate reliably with whatever version of Windows we happened
to be running. Getting a WDM driver right is a challenging task. As you have
found by your own web surfing, many of the USB Serial Adapters on the market
don't operate reliably and again it would not be surprising to find that
the bugs were due to the software writers struggling with the vagaries of the WDM.
In recent years, anecdotally there have been great improvements in the 'out of
the box' experience for many USB connect devices as manufacturers invest the
time, money and energy into 'getting it right'.

All planetarium programs on the market today that provide a telescope interface
capability expect a RS-232 serial comms device. Therefore there is a certain
amount of 'chicken and the egg' going on. Telescopes with non RS-232 comms
capability would be supported by very few software applications. However, until
telescopes using other interface technologies other than RS-232 become
ubiquitous, many software applications developers are unlikely to invest in
supporting them. However, this will change over time.

Keep in mind that RS-232 is alive and well and will be in use for many years
to come. For example, one of the protocol layers of the popular Bluetooth
wireless technology known as RFCOMM is purposely designed to mimic
RS-232 serial comms at the transport level.

However, getting back to actual practical advice for one moment, the Keyspan
USA-19HS USB Serial Adapter and its associated drivers are highly recommended
for telescope control applications and it is the reason we supply them ourselves.

Best Regards

Gary

[Doomsayer]

Serial is the connection of choice for most remote pro-end observatories such as the numerous Paramount driven scopes in the hills around the "New Mexico Skies" site in the US. I was advised by a couple of experts from there that they don't use the USB port on their Paramounts, if one is installed. Considering this is the high end of the amateur equipment market, it still says a lot for serial ports. I'd assume they would still connect serial deviced via a serial-usb converter at the PC end. I certianly don't have any issues with serial connection of my Paramount. Image data transfer is usually best dealt with by an ethernet solution in that situation - cable length and cable quality can be a trap for large dataset transfer,

I guess the longer term concern is that future operating systems may not support such old-style connections.

[Starkler]

In my work a laptop is a tool used mainly for programming and maintenance of external devices. Eight times out of the ten the device will have a serial rs-232 port, most of the rest will have a LAN port. I have never seen any device which wasnt specifically a computer peripheral come with a usb port.



Yep i know. A year or so ago there was a Dell model you could get. Im not sure about now.
Instead of blaming the device designers I would rather blame the laptop manufacturers. If only they still included the serial port, which must cost something like a whole $2 to include at manufacture, life would be so much easier for those who use their laptop as a tool to interface with external hardware devices.

[Tandum]

You can always get a pcmcia to serial card. This adds a real serial port to your laptop not some hockey usb converter. I haven't seen these in the PCMCIAExpress format your now getting in brand new laptops. Also from a programmers point of view, there are so many routines functions and bits of code already written for 232 comms it's to easy to use what has already been written.

http://www.ieci.com.au/products/Product_Page2.asp?Product_ID=86

http://www.computeralliance.com.au/parts.aspx?qryPart=4695

[AndrewJ]

I bought a HP NX6120 about a year ago
Real serial and parallel ports and 4 USB2 Plus Lan + bluetooth + firewire.
Serial port gets most use with my astro apps, and works without fuss.

It would be nice is if the lappie manufacturers made a unit with a set of cut down 3 wire RS232 connectors, and a red backlit membrane keyboard, and a top quality screen with powerful graphics card, high capacity raid HDDs
and USB reserved for the external coffee warmer.

Andrew

[White Rabbit]

Well I guess I got my answer, the manufacturers are sticking with it because the customer is happy with this. Thats fair enough and good enough for me.

[White Rabbit]

I should state as well that my frustration is not just with astro gear. I'm an audio engineer (I use the term engineer very loosely) and a lot of the digital equipment we use uses serial as well. So this started a long time ago for me lol.

[[1ponders]]

I use one of these and it works a treat. Why have only one Serial port when you can have 4
http://www.streetwise.com.au/product_info.php?products_id=4660

but shop around the price varies considerably

http://www.expansys.com.au/p.aspx?i=147729

[Bassnut]

Yes, exactly. We at GRAS use serial wherever we can (incl PMEs), even if it means installing extra serial cards. Although at home I use USB, the more complicated your rig gets, the more problimatic USB gets (drivers etc). The same for industrial applications.

BTW, for example, I tried the QHY5 guide cam (USB powered) with my lappie. Any USB extention cable longer than 2foot caused havoc (was OK with longer on a PC). USB powered devices are convienient (not possible with serial really) but can be fraught with problems.

[edwardsdj]

USB leaves devices completely hidden to the programmer under Windows.

With RS-232 you can just open the port and talk. This makes it possible for many people to contribute software that works easily with RS-232 devices.

With USB, if your device is in one of the standard device classes (things like webcam, etc...) you are fine. If not (telescope mounts are not a standard USB device class) then you are up for writing mountains of hardware-level driver code to make it work. Driver development under Windows requires expensive development kits and a lot of mucking around compared to user software.

I'm always much happier to see an RS-232 port because I know I can reverse-enigineer the protocol with readily available equipment and write my own control software without having to code drivers at the hardware level.

Have fun,
Doug

[citivolus]

My personal preference for shifting away from RS-232 type serial interfaces is TCP/IP over ethernet. It is the only current viable alternative that is not significantly distance limited, and through the use of DHCP can provide you with multiple levels of granularity of configuration.

Sure it isn't as simple as RS-232, but with the current cost of network chipsets, can be implemented at very minimal cost to the manufacturer at the hardware level. The caveat of course is that they have to write decent firmware or the interface is useless.

I wouldn't advocate USB for the simple reason that it probably costs as much at Ethernet to implement, and is very distance limited.

[edwardsdj]

Most equipment that has ethernet ports runs a full-blown operating system (like Linux) in order to implement the network stack. This is why most home routers with ethernet ports run Linux.

Both TCP/IP and USB are very software-heavy. They put all the work into software. TCP/IP is a lot easier to deal with than USB from a software perspective, but when developing an embedded device, the complexity of running a full operating system in practice just leads to frequent crashes.

How often do set-top boxes, wireless routers, etc... need rebooting these days? It's because they run Linux which, while reliable is just vastly more complicated than having the system just doing what it needs to do (like the old days).

RS-232 is really simple. It is easy to write software for it in embedded controllers. Most embedded controllers have built-in RS-232. Some do have embedded ethernet, but I'm not sure if you actually get a TCP/IP software stack with these.

The kinds of microcontrollers used in telescope mounts would have small amounts of RAM (typically 4kb to 128kb) and reasonable amounts of ROM (maybe 512kb to 4MB). Moving to TCP/IP for this equipment at the moment would involve running Linux on the telescope mount (like in a wireless router). Heaps more features....heaps less reliability.

Anyway, my 2 cents.

Have fun,
Doug

[Tandum]

I guess It should also be added that USB has a practical limit of 5 meters where as 232 can run 50 Meters.