USB to Serial Convertor

[TheThing]

Need a bit of help from the computer whizzes out there please?

I need a USB to Serial convertor with a FTDI Chipset to run a LX mod SPC900. I've tried a fairly (well very!) cheap cable from Amazon, but it doesn't seem to recognise the cam. I've been advised that the FTDI chipset is the way to go.

I've done a quick Google search but only found one place that sells them specifically and they are out of stock!

How can I tell if a cable has a FTDI chipset 'in it'? Any ideas where I can get hold of one cheaply?

Thanks!

[Merlin66]

Been there, done that....

I now only use the Keyspan usb>serial adaptors...it works 100% with ALL my software and hardware. Never let me down.

Highly recommended.

[brantuk]

Astronomiser also do hubs and converters that will work for astronomy gear - they also mod spc900's and supply cables to go with (which can be purchased separately)

[NickMorris]

I'll second what Merlin66 says - the keyspan usb -> serial is the ONLY way to go. Have spent many hours with problems from other manufacturers. Expensive but nothing more reliable.

photonboy

[Beyond_Vision]

Would this do the job

FTDI|US232R-100|CABLE, USB TO RS232, SERIAL CONVERTER | Farnell United Kingdom

Regards

Kevin

[E621Keith]

Are you using a laptop? Does it have a PCMCIA or a express card slot? If it does, then a PCMCIA or express card to RS232 may be more reliable than USB-RS232.

[pete_l]

I need a USB to Serial convertor with a FTDI Chipset to run a LX mod SPC900.

I've built a couple of LX mods now and I haven't needed an FTDI chipset for either of them. In fact I've used a cheap-as-chips, bottom of the range USB-Serial converter.

The "received wisdom" that I've read in many places (possibly because the same fundemental advice gets copied from one source to another) is that the USB-Serial somehow needs to supply + & - 12Volts, per the RS232 standard, which is then level-shifted in the LX mod to logic 0 and +5Volt signals.

What i've done is cut out all that stuff as it's essentially duplication. The USB-Serial converter supplies the signallng pins we use for LX as 0 and +5Volts, which is (I expect, I can't prove it) why these "cheap" units fail to wok with the full-on LX mod. By ripping out the level conversion transistor from the LX mod, I've fed the USB-Serial's signals straight into my LX's logic and simplified the whole thing.

For reference, the USB-Serials I've used are available from many places on eBay for a couple of ££ (I've just checked: £1.49 with free P&P) and look like this:

with the electronics in the body of the device, which is made from a sort of green gel. You can cut this away and remove the 9-pin connector and then just wire the LX mod to the USB-Serial circuit board. It's much smaller like that as the USB-Serial circuit is only about an inch long.

They come with a mini-CD that contains the driver for the chip. Just load that first, install the drivers, then plug in the device and it just works. I've added a couple of LEDs (via current limiting resistors) tot he two LX control signals, so I can see when the USB-Serial initialises, as the LEDs flash. It also provides a visual indication of when the exposures are being taken.

[TheThing]

Thanks for all the advice guys.

My 'chip as chips' one from Amazon has loaded ok and shows as being connected, but when I add the camera, nothing.

I've e-mailed Andy at Astronomiser, who has what I need and is guaranteed to work or he'll give full money back. Can't say fairer than that!

I've got to hang on for pay day, but I'll get one from him shortly and report my findings. I must say that Andy has been excellent with advice and communication. He replied to my e-mail within about 2 mins!

[black5f]

Hi. Guaranteed to work or money back is the way to go! Otherwise it gets too complicated, RS232 uses 12V to transmit but somwhere around 3V at the reciever end should work as it's designed to work over some length. But 30 meter leads are only used by about three people in the world so to save the planet etc, power saveing profiles cut this down or even off. USB is only 5V, some will give a higher current to enable devices to be charged but this is outside the standard. Power save etc etc ...not worth worrying about. We use FTDI ones, they seem more reliable if you have the latest drivers etc. Used to use the PMCIA cards and they were nothing but trouble. Bite his hand off! Tom