Planetarium control help? (Skywatcher)

Ok, please bear with me - I've read as much as I can on this and would like some advice.

I have a HEQ5 mount (just arrived!) and a GPS mouse. Now the GPS mouse came with a RJ45 - serial cable and a serial-USB converter together with drivers. Can I use this cable via the secondary port on the handcontroller to enable PC control? Or am I barking up the wrong tree and need something else?

I have ASCOM and the appropriate drivers installed, along with Cartes du Ciel 3.

Any advice appreciated. Cheers.

Don't know about barking up the wrong tree, but I don't think what you're asking will work.

I had a HEQ5 Pro mount same as you, recently sold for NEQ6 Pro, but pretty much the same. Also used EQMod/ASCOM and CdC etc. I reckon forget connecting through the hand controller, I've read about issues with the PC direct mode on them.

Just connect your notebook directly into the mount's RJ45 hand controller port with a serial-USB cable. See the EQMod website for more on that. http://eq-mod.sourceforge.net/ I made my own EQ Direct cable.

The GPS will just plug into your notebook only.

If you're asking about using the cable that came with the GPS to connect the PC to the hand controller, be careful! There is no standard for wiring of serial cables, and if you get it wrong, you could fry the hand controller, the mount, the PC or all three! The pin-out of the cable has to be correct, so you would have to verify that with a conductivity meter. And the PC cable port on the handset is RJ-12, not RJ-45, so an RJ-45 cable won't work.

You should already have a cable that works, though - the cable that came with the mount for downloading firmware is the same one you use for PC control through the handset. The cable that came with my Atlas is a little short, though, so I determined the pin-out and fabricated a longer one. Attached is a drawing I made of the Atlas serial control pin-out, it will be be same for the HEQ5.

If you're asking about the Serial-USB converter, some of them work to control the mount and some don't. My laptop PC has an RS-232 port, so I haven't used the converters, but you can give it a try. Use the cable that came with the mount until you get or make another one.

The Synta mounts with the SynScan controller will work with Cartes du Ciel and ASCOM with or without EQMOD software, and if you use EQMOD, you can use the mount with the handset or you can get an EQDIR module and use it without the handset. If you don't use EQMOD, you must attach the serial cable to the handset, and configure the mount as one of the Celestron Advanced Series EQ mounts in the ASCOM dialog within Cartes du Ciel. With EQMOD, you can connect the serial cable to the handset or to an EQDIR module.

I have used my Atlas mount in all three configurations with Cartes du Ciel. Going through the handset with EQMOD requires recent firmware in the handset so that you can enable PC DIRECT mode in the handset. It works fine, but there are problems if you try to take the handset out of PC DIRECT mode and use the handset for anything other than directional and slew rate control while connected through EQMOD.

My recommendation though is to get an EQDIR module and use it with EQMOD instead of the handset. You can buy an EQDIR module at http://www.shoestringa​stronomy.com, and they sell long cables too. You will then need a joystick or gamepad to control the mount in lieu of the handset. I use a Logitech Cordless RumblePad. EQMOD gives you much better control of the mount than the ASCOM Celestron interface, and the EQDIR supposedly gives you better tracking/guiding performance than going through the handset with EQMOD, though I couldn't really tell the difference.

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Many, many thanks guys. I've bitten the bullet on the EQDIR module (USB) in the end as I needed to get some "supplies" from FLO (can't get on with the supplied finderscope so I'm going to give a reflex sight a try out...)

Just to make sure you're getting the right module, the EQDIR is not USB- it's RS-232. It must be connected to an RS-232 port, but if your PC doesn't have an RS-232 port you can use a USB to RS-232 adapter, though from what I've heard not all of them work with the EQDIR and EQMOD. There are USB to RS-232 cables on the market that produce the correct signal levels, but to the best of my knowledge there aren't any that interface with the HEQ5 mount out of the box - you would need to determine the correct pin-out and add an RJ-45 plug to the cable.

RS-232 uses 12 volt signals and has relatively high current capacity, while USB uses 5 volt, low current signals. That's why you can't hook a serial cable directly between the mount and your PC's RS-232 port - smoke would ensue. The EQDIR converts the RS-232 signals to low voltage TTL signals, as does the hand controller if you use it instead of an EQDIR. The advantage of the EQDIR over the handset connection is supposedly that the multiple cascaded connections in the handset slow down the data flow compared to the EQDIR, which doesn't really affect go-to's, tracking, slewing, etc., but could affect autoguiding performance.

Most PC's these days don't have RS-232 ports, so if you need a USB to RS-232 adapter, I recommend getting one from a vendor you will be able to return it to if it doesn't work. In the Links section on the EQMOD Yahoo group site, there's a link to one that reportedly does work. Again, I don't use an adapter so I can't recommend one, though I'm sure there are many people who do use them with an EQDIR. Hopefully some day soon the manufacturer of these mounts will abandon the old RS-232 interface for USB.

Hi, Don, the one I've ordered was advertised as being a USB version - I guess I'll find out when it arrives!

Thanks again for all the info!

OK, my mistake. I googled EQDIR-USB, and I see that there is a vendor selling an EQDIR-type product that connects directly to the PC's USB port (http://www.xagyl.com/s​tore/home.php). They sell two versions, EQDIR-USB-2 for the HEQ5/Sirius and EQDIR-USB for the EQ6/Atlas. So it eliminates the need for a USB to RS-232 adapter, and the price is quite reasonable. Not sure just how it will work, since the EQMOD software wants to know a COM port number, but I guess the driver you download from that site lets it emulate a COM port.

Let us know how it works!

Don

Typical that you "need" a different one for a different mount...

I'll report back once it's arrived!

Cheers