DISCLAIMER:
You can use the information on this site COMPLETELY AT YOUR OWN RISK. The modification steps and other information on this site is provided to you "AS IS" and WITHOUT WARRANTY OF ANY KIND, express, statutory, implied or otherwise, including without limitation any warranty of merchantability or fitness for any particular or intended purpose. In no event the author will be liable for any direct, indirect, punitive, special, incidental or consequential damages or loss of any kind whether or not the author has been advised of the possibility of such loss.
WARNING:
Circuit modifications implemented on your setup could invalidate any warranty that you may have. Use this information at your own risk. The modifications involve direct access to the stepper motor controls of your mount. Any "mis-control" or "mis-command" / "invalid parameter" or "garbage" data sent to the mount could accidentally activate the stepper motors and allow it to rotate "freely" damaging any equipment connected to your mount. It is also possible that any garbage or invalid data sent to the mount could cause its firmware to generate mis-steps pulse sequences to the motors causing it to overheat. Make sure that you perform the modifications and testing while there is no physical "load" or dangling wires on your mount. Be sure to disconnect the power once this event happens or if you notice any unusual sound coming from the motor assembly.
In order to connect a PC/Laptop directly to the EQ mount an interface device is required. This device is refered to as an EQDIRCT. Connection must be made through such a device NEVER CONNECT DIRECLY YOUR PC DIRECTLY TO THE MOUNT. There are two EQDIRECT options presented here.
- EDIRECT-RS232 - requires the PC to have an available RS-232 port or a USB to Serial convertor.
- EDIRECT-USB - this includes embedded USB-Serial conversion
Also be aware that when using an EQDIRECT-232 device in combination with a usb-232 convertor you should make sure the usb-232 convertor is of a type that supplies true (-9V,+9V) RS-232 signals.
Both types of EQDIRECT are releatively easy to build by anyone with limited electronics experience however many folks choose to opt for ready made commercial products (see vendors). Please note that The EQMOD Project has no affiliation with these vendors. If/when disucssing EQMOD publically please take care to present all EQDIRECT options (perhaps by reference to this page) in addition to any personal recomendations you may have.
EQDIRECT-RS232
Figure 1 shows a diagram that will allow you to directly connect your PC to the Mount's DB9 Handcontroller Port. The port contains both the 12V power lines and the two TTL level serial data lines. It allows the user to send the commands from the PC's serial port to the mount's handpaddle DB9 port. The circuit utilizes two major components; a RS232C-TTL converter (MAX232) chip and a 5 Volt voltage regulator (7805) that supplies power to the max232 chip. The 7805 source of power comes from pins 1 and 8 of the mount's DB9 connector. Extra care should be provided in avoiding these lines to be interchanged/shorted to the TTL level lines (pins 9 and 6). Pins 5 and 4 are ground pins.
Figure 1: Circuit Diagram for Direct PC access through the mount's DB9 connector
EQDIRECT-USB
An EQDIRECT-USB convertor consists of a combined USB serial port that provides TTL outputs. Such a device is avilable from FTDI called the TTL232R, and comes integrated into a USB cble and connector. Please be aware that FTDI produce a similar product, the TTL232R3V3, but due to lower signaling voltages this will not work. A driver is installed on the PC and the TTL232R appears as a standard com port. There is an additional advantage in that unlike many usb-serial devices the com port number of the FTDI device, once assigned, will not change when plugged into a different physical USB port.
Data sheet here: http://www.ftdichip.com/Documents/DataSheets/Modules/DS_TTL232R.pdf
To create the EQDIRECT-USB all theat is needed is to connect a 9 way "D" type plug to the flying lead of the TTL232R. The connections are as follows:
Solder Pin 6 of the 9 way D-type Plug to the Orange wire.
Solder Pin 9 of the 9 way D-type Plug to the Yellow wire.
Solder Pins 4 & 5 of the 9 way D-type Plug to the Black wire.
For those with HEQ5-Pro you will need to splice an RJ45 cable to the flying lead of the TTL232R. Connect as follows:
Solder Pin 4 of the RJ45 to the black wire
Solder Pin 5 of the RJ45 to the yellow wire
Solder Pin 6 of the RJ45 to the orange wire
