EQMOD + PCDIRECT or EQDIRECT. Which cable for Synscan EQ5 mount?

Posted by XTSee on 22nd October , 2012

Fairly recently I’ve started using EQMOD software with EQASCOM to control my Synscan Goto Upgrade Kit for my EQ5 telescope mount with my C6-SGT scope. There are various advantages to using EQMOD. It’s free for a start, but don’t let that fool you into thinking this is average quality software. EQMOD has quite a few nice features, and is designed for professional equatorial mount control and I highly recommend it.

After some investigation (and it seems quite a few other people on forums get confused about what is possible) it turns out I am able to use the standard RS232 serial cable supplied with my Synscan Upgrade kit when the mount is set to use PCDIRECT mode.

Normally I use this standard cable with a USB to Serial converter plugged into the bottom of the SynScan Hand Controller unit to allow planetarium software like Carte du Ciel or Stellarium to control my mount via the Celestron ASCOM driver.

It turns out that EQMOD can also use this cable to control the mount. Well this would seem to be the logical conclusion wouldn’t it? Planetarium software can control it, so why not EQMOD too? This is where the confusion sets in!

When I first started reading about EQMOD I got the impression that it had to use a special adapter cable plugged directly into the Hand Controller RJ45 socket on the mount (without the hand controller in use at all) and via an electronic box called an EQDIRECT adaptor, but depending on where you get this from, and get the cables required on either side of it, the cost can be anything from £40 to £80, although you could build the unit yourself to reduce the cost. Well I’m going to tell you the cheapest and easiest way of making this cable (about £13+delivery). By the way, all this information is available on the EQMOD site.

EQMOD works in a different way to other software because it communicates with the mount electronics more directly, rather than going via Celestron driver software thru the hand controller. This means control signals are quicker and more accurate.

The EQDIRECT adapter is designed to convert the voltage levels to operate the mount when connected in this “direct” way, and it also protects both the laptop and the mount from electronic damage if you plug them incorrectly. Places like Shoestring Astronomy build such a unit, and supply the required cables, but technology has moved on and there is actually a simpler and neater type of cable which does away with the EQDIRECT “box” altogether (although it is still referred to as an EQDIRECT cable, because simply put “it is a cable used by EQMOD to plug directly into the mount“).

Anyway, back to the point. I was excited about trying EQMOD, but it seemed as though I would have to fork out a bunch of money, and wait for a cable and adapter before I could do so.

The standard cable can not be plugged directly into the hand-controller port on the mount! It is not designed for this, it has an RJ11 male connector anyway, and could damage the mount electronics if you added some kind of RJ11 to RJ45 adaptor plug.


This is where PCDIRECT comes to the rescue - although it is recommended that this method is used only for trying out EQMOD. For long-term use the special EQDIRECT cable described above should be obtained instead (more on this in a moment).

PCDIRECT mode sets the hand-controller unit to pass these different signals from EQMOD straight through its circuitry to the mount, effectively bypassing any interaction with the hand controller unit itself. In a way PCDIRECT mode acts as if it were a simple EQDIRECT adapter cable!

The trouble with PCDIRECT is that if you were to try also to use the hand controller functions to control the scope, e.g. slewing, or the tours, etc, both the hand controller (plus any other software using ASCOM normally) and EQMOD could get very confused about where the scope is pointing, or they might corrupt the control signals being passed. Certainly not what you want if you have spent time aligning the scope. So this is why you should get a proper EQDIRECT cable if you intend to use EQMOD seriously.

The good news is that PCDIRECT mode can be used by plugging the standard cable into the bottom of Synscan (or Celestron) handcontroller as normal (in the RJ11 port), and then set PCDIRECT mode on, which can be found in the Utility menu.

Assuming you’ve installed EQMOD+EQASCOM followed by the latest ASCOM Platform 6SP1 from the ASCOM site proceed as follows:-

Plug standard USB>Serial adaptor+RS232 cable into the RJ11 on Handcontroller.

Turn on the mount, press Enter on the hand controller multiple times quickly to skip thru the Date,Time, Lat/Long settings accepting whatever values were already there, it really doesn’t matter, and after the Polaris hour-angle display press 2)NO to ignore alignment. This leaves you with the SETUP> menu displayed.

(No settings/alignment need to be done, PCDIRECT mode is a dumb passing of signals, it doesn’t care about anything set or controlled by the firmware in the hand controller. EQMOD is the only thing you need to work with. You perform everything in EQMOD; date/time set by the laptop, geographical lat/long from manual entry or better a USB GPS plugged into the laptop, slewing by mouse/keyboard control or better a USB or bluetooth gamepad, polar alignment with EQMOD as an aid to accurately setting hour-angle, and sky alignment in conjunction with the Sync function in planetarium software using as many stars as you wish, 1,2,3 or up to 1000).

Choose Utility menu, scroll to PCDIRECT, and press Enter (shows message “PC Direct Mode: Press ESC to exit“, leave like this, and don’t touch the handcontroller until the end of your nights session).

One time setup:-

2. Choose EQASCOM, click Driver Setup button. Mount options Type should be SyntaEQ (no need to change/set Custom mount RA/DEC).
3. In EQMOD Port Details you should only need to change the COM port to match. Timeout(1000), retry(1), Baud(9600) remain as standard. Note the Find (binos) button sometimes fails to detect the mount (ignore this).
4. Click OK (setup closes).
5. Click Test Connect (this should work) and…
6. EQMOD ASCOM EQ5/6 window opens and will be flashing PARKED. Click UNPARK.
7. Click the “star” button and you should hear the RA motor start tracking.
8. Choose Rate 4 from the dropdown, sets rate 800 for both RA & Dec.
9. Click N,E,S,W and should slew proving working ok.
10. Click Park, then in the Toolbox screen click Disconnect.
11. Exit Toolbox.

Should now be able to Start>EQMOD>EQASCOM>EQASCOM_Run for normal operation.


I purchased my EQDIRECT cable which is a TTL-232R-5V-WE from EasySync Ltd for £12.99 (the linked page has tech docs and USB driver downloads). This cable has a miniature FT232RQ converter chip built into the USB plug end of the cable (the equivalent of what is in the larger/older style EQDIRECT junction boxes). It provides TTL level signals at 5 volts (5V).

The -WE (on the end of the part number above) means bare wire-ended (i.e. without any kind of connector on it), and this is the only bit of making up that is required. You need to find a techy friend, computer shop or someone who makes up network cables who has a tool that can crimp an RJ45 male plug onto the wire end of the cable. The stripped wires are slightly too thick to go into the RJ45 wire holes, and need thinning just a little and then tinning with solder, to insert into the RJ45 plug ready for crimping. It’s a little bit fiddly to get it just right, but well worth doing this relatively simple job to save your money.

Only the Black (Ground), Yellow (RX) and Orange (TX) wires are necessary, the other 3 can be cut-back making sure they cannot short together. On the RJ45 plug Black goes to pin 4, Yellow to pin 5 and Orange to pin 6, as detailed in the diagram at the bottom of this EQDIRECT page. (Note: I messed up first go, and crimped shorting a couple of the wires because I had pushed them in too hard, so had to cut off the plug, strip back and retry with a new RJ45. Second go worked, and had not caused any damage).

You now have a single neat EQDIRECT cable without any bulky adapter box mid-way.

You will need to download and install the USB driver software from the links available on the purchase page at EasySync. Note the benefit of the driver is a static COM port number, which conveniently remains the same number even if plugged into a different USB port.

Plug your new EQDIRECT USB>RS232 TTL lead into the USB port and into the RJ45 on the mount normally used for the HC (the Handcontroller will not be plugged in at all).

Turn on the mount (no beeps since the HC usually emits sound, but isn’t connected).
Follow steps 1-11 exactly as above except choose the COM port for the new lead.

In Cartes du Ciel for Scope connection, select EQMOD ASCOM EQ5/6 (if EQASCOM_Run is not already running CdC will start it up).

Note that it is generally better to start EQASCOM_Run manually (will show in Systray, where it can be Exited when finished). This means it runs continually, rather than being auto started and stopped by other software using the mount, which occasionally leads to problems.

Disclaimer: While this article aims to be helpful and may apply to other popular mount types, I accept no responsibility for inaccuracies or damage resulting from incorrectly matched cable types. Please ensure you order the correct items for your particular mount by completing your own research.

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