Pelco to servo controler

[gazz 0]

I already have some PTZ domes in the roof of my aviary, the rest of the cams are fixed, and i point them at the nest sites the birds choose so i can keep an eye on the chicks,

 

i rekon the parents know when i'm watching tho, as they are very good at standing on the nest so they block the view of the chicks when feeding them... and that's the bit i need to monitor the most... so watch for chicks not being fed etc.

 

So i thought i'd mount the fixed camera's i have on pan and tilt mounts, and i figured the cheapest way to do that would be to get 2 standard hobby type servo's (the type used in radio controlled planes, cars, boats etc)

mount one ontop of the rotating part of the other, and i can have pan and tilt with the camera mounted on the upper servo,

 

only problem is i want to control the servo's with my existing cctv system (concept pro VXH264, and the matching VA-KBTPRO+)

So i need a way to convert the pelco commands to servo commands,

 

I looked at using an arduino and writing the code my self to do that, but coding is not my strong point, and i need a few other boards to get the RS485 signal to TTL levels for the arduino to understand, before i beging ti interpret the pelco commands and translate them into servo movements.

 

So i was wondering if anyone knew of a ready made, and preferably dirt cheap board that can take a RS485 pelco input, and output something a pair of servo's will understand.

[k8_fan 0]

I searched to find if anyone had dealt with this problem or not.

 

In my situation, I'm needing to shoot HD, but HD speed-domes are far out of my budget, and recording the feed is also very expensive. But consumer HD camcorders are cheap, and pan-tilt mounts driven by robotic hobbyist servos are very cheap. On the other hand, that market seems to have very few decent controllers, certainly nothing comparable to the very mature pan-tilt-zoom controller market of CCTV. The default controller in the hobbyist market is a radio control with a pair of spring-loaded joysticks intended to return to center.

 

I believe there is a market for a board to take Pelco pan-tilt-zoom protocol signals and control a pair of standard servos for pan and tilt, and (optionally) convert the zoom signal to IR LED flashes to control a camcorder.

 

Any electronics designers interested in coming up with a circuit to do this?

[ChrisL 0]

You are trying to re-invent the wheel on something that is already out there / working. To answer your question generally, not, its not going to work.

 

If you aren't going to see the HD Camcorder on the cctv system, why force the controls there?

[k8_fan 0]

You are trying to re-invent the wheel on something that is already out there / working. To answer your question generally, not, its not going to work.

 

If you aren't going to see the HD Camcorder on the cctv system, why force the controls there?

No, you misunderstand. I am shooting concerts, not going to a CCTV recorder. I'm recording HD to the SD card. The problem is that the pan-tilt systems intended for the concert world are either $50 plastic consumer garbage or $2000. I'm trying to take advantage of the high quality and relatively inexpensive tools that exist in the CCTV world. Again, I'm NOT interested in CCTV applications - I'm wanting to use the rugged, inexpensive controllers available in the CCTV market. to control the excellent quality servos available in the robotics hobbyist market.

 

I want to control one of these: http://www.servocity.com/html/ddt540_direct_drive_tilt.html

 

...With one of these: http://backbone5599.en.made-in-china.com/product/QeEnzJrxtpYo/China-Ptz-Keyboard-Controller-on-Vehicle-IDRS-KB10-.html

 

I need the circuit to translate the Pelco interface of the latter to the servo control signals of the former.

[ChrisL 0]

Ok, sorry, I think I understand now.

 

So something like this:

http://www.pelco.com/sites/global/en/products/camera-solutions/range-presentation.page?p_function_id=9504&p_family_id=10220&p_range_id=2864

 

Better built than a $20 servo, not $2000, and runs off of PTZ controls.

[k8_fan 0]

Ok, sorry, I think I understand now.

 

So something like this:

http://www.pelco.com/sites/global/en/products/camera-solutions/range-presentation.page?p_function_id=9504&p_family_id=10220&p_range_id=2864

 

Better built than a $20 servo, not $2000, and runs off of PTZ controls.

Yeah, I looked at that, but it's overkill for my purposes. You see, I'm carrying these with me to a show, and this "mini" pan-tilt head is 8" wide. I need to carry two of these, and Pelco pan-tilt heads are built like a truck and weigh nearly as much. The Servocity units I'm looking at are made of plastic. While that might suck in a CCTV application where punks are trying to tear them down, it sounds like heaven to me. I don't need something that can move an 8 lb camera when my camera only weighs 1 lb - all that extra capacity is just bulk and overkill for my purpose.

 

I actually carry enough cameras, tripod, cables, mics, stands, mixer, quad-split and power to do a 5 camera concert shoot in a backpack. Put it this way, I moved from RG-59 cables to RG-174 to shave a couple of pounds off my rig. Every ounce matters when it's on your back.

 

Edit to add: I might consider buying a Pelco protocol pan-tilt head and stripping it down to lighten it. Are there any especially small pan-tilt heads? Like ones intended for bullet cams? But that still leaves me without the other part of the equation, which is to convert Pelco zoom control signals to Canon IR or Control-L signals.

[Horizon 0]

Hi there k8_fan.

 

The Pelco mount the ChrisL has pointed you to is a fixed speed mount - when moving, it moves at a constant speed. It would also need a Pelco decoder. Or you could hook up a set of push buttons onto the end of a length of Cat5 to remote control it. It also needs 24VAC for the motors, so you'd need access to mains power at your events.

BTW, that is a "light duty" mount, weighing a measly 4kg. There are other knock-off copies of this design from China. They cost a lot less, and are probably lighter weight, using plastic instead of steel and aluminium.

[k8_fan 0]

Hi there k8_fan.

 

The Pelco mount the ChrisL has pointed you to is a fixed speed mount - when moving, it moves at a constant speed.

The size and weight pretty much eliminated it from consideration right from the start.

 

It would also need a Pelco decoder. Or you could hook up a set of push buttons onto the end of a length of Cat5 to remote control it. It also needs 24VAC for the motors, so you'd need access to mains power at your events.

I'm shooting concerts in venues, so I always have AC power available.

 

BTW, that is a "light duty" mount, weighing a measly 4kg. There are other knock-off copies of this design from China. They cost a lot less, and are probably lighter weight, using plastic instead of steel and aluminium.

Right. That's 8 lbs, and the 2 units needed would add 16 lbs to the 65 lbs I'm already carrying on my back. By contrast, the Servocity tilt mount I posted in my first post weighs 9.8 oz, or .3 kg.

 

Please, this has gotten off-track. CCTV has needs that do not apply to my situation. For instance, I am working inside a music venue. There is no wind load, no ice build-up, etc. I need exactly what I described, which is a way to use a Pelco protocol controller with a pair of standard hobbyist servos.

 

I posted to a cheap, astonishingly light tilt system that allows me to mount a 1 lb camera that rotates on the camera's center of gravity:

 

http://www.servocity.com/html/ddt540_direct_drive_tilt.html

 

That unit mounts onto another servo to provide rotation:

 

http://www.servocity.com/html/ddp155_base_pan.html

 

I have every reason to believe I can build the entire pan/tilt head, control included, and keep the weight under 1.5 lbs. What I need is to be able to take advantage of the huge scale of economy of the CCTV world to purchase inexpensive, flexible and mature Pelco protocol PTZ controllers and have them control a much smaller, lighter and far faster hobbyist servo driven pan tilt heads:

 

[gazz 0]

Unfortunately i got pretty much the same response on electronics forums, they all say 'just buy a proper ptz mount' or use servo's and run wires back to a dedicated controller made out of bits of old computer joystick and sticky tape.... or even connect the servo's to a RC reciever, and use a RC transmitter to move them.

 

The protocol is pretty simple, if you understand the programming languages, which i dont very well,

but i figured i'd use an arduino, i'd need an RS485 'shield' which is basically just a rs-485 to TTL converter chip mounted on a board that plugs straight into an arduino,

 

this gets the rs-485 signals safely into the arduino, i then need to faff about getting the arduino to listen to the commands, then translate them into servo movements and output to the servo's,

 

The servo side is already present for arduinos, you just need to tell it what angle in degrees and on which pin the servo you want to move is on, and it'll do it, it's just translating the pelco commands into something the arduino can understand and work with.

 

prolly a 5 minute job for someone who knows a programming language, but for me i may as well be trying to fly to the moon on my pushbike.

 

anyhoo, the pelco protocol is:

http://www.commfront.com/RS232_Examples/CCTV/Pelco_D_Pelco_P_Examples_Tutorial.HTM

 

So need to figure out how to get say 'FF 01 00 04 3F 00' into something like 'pin1, servo.write(160)'

tho that would just take the servo to 160 degrees, need to add the code to move the servo constantly untill a stop command is recieved, or untill the servo reaches the end stop/180 or 0 degrees is reached, but that code is already present too.

 

 

There is one person on youtube who has done just this:

But he dosent seem to want to give the code out, despite a few people asking including my self... and possibly you?? someone wanting to move a 1lb camcorder.

[k8_fan 0]

Unfortunately i got pretty much the same response on electronics forums, they all say 'just buy a proper ptz mount' or use servo's and run wires back to a dedicated controller made out of bits of old computer joystick and sticky tape.... or even connect the servo's to a RC reciever, and use a RC transmitter to move them.

The commercial CCTV pan-tilt heads are perfectly fine for their intended purpose, but there are a lot of criteria they are designed for that just don't apply in my case. And probably yours as well.

 

There is one person on youtube who has done just this:

But he dosent seem to want to give the code out, despite a few people asking including my self... and possibly you?? someone wanting to move a 1lb camcorder.

I saw and commented on that. His Livejournal blog is in Russian, and he seems to be constantly hacking new hardware projects. I've known more than a few hackers who can invent stuff all day long, but once done, they lose interest in documenting or commercializing anything. As I said in my comment on that video:

 

Looks very simple - a crystal, a PAL, a couple of diodes and a trim pot? I could so easily build that. Feel like sharing? I'd be overjoyed to lay out the board. I might need to control more powerful servos to handle a 1 lb camcorder, but this is exactly what I'm looking for.

 

I don't know that the chip is a PAL, but that looks familiar.

[gazz 0]

Yup, i want to move some cheap cameras a little bit in my aviary, so i can adjust the position they point at the nests a little, to see the chicks being fed when the parents are standing so they block the cams view occasionally,

the camera's are those round bodied ones, about the diameter of a deodorant can, and about 4 inches long, weigh next to nothing,

 

I need no security, no weather protection, no over engineered so it wont break type durability, really the opposite of what most people want in a CCTV situation,

 

a couple of hobby servo's will be ideal, cost about a tenner the pair, rather than 5 times the camera's cost for a proper ptz mount,

 

I was also thinking of making a kind of turntable, the pan servo would rotate the camera mounted on the edge of the turntable around an axis, so it could position the camera anywhere around the perimeter of the nest site, that case the servo would be modified for continuous rotation, but i still need to translate the pelco commands into servo left and right commands.

 

 

But it's the code he's put on the chip that does the magic,

unfortunately there are a lot of people on youtube who are just showing off what they have built as a way to 'prove' they are better than others,

i guess that's half of the reason youtube exists, but it's much better when people help each other out with similar projects.

[dvarapala 0]

This would be easy to do with an embedded microcontroller experimenter board like the Arduino. Hobby servos are easily controlled by PWM outputs from the microcontroller, and you can send commands to the microcontroller from just about anything you want (via Ethernet, USB, or even a standard CCTV PTZ joystick over RS-485 using Pelco protocol if you so desire). The only catch is you're going to have to write the software yourself (or pay someone to do it for you). The Arduinos are designed for use by artists, so they're about as easy to program as embedded systems get, and might be within your capabilities.

 

Just for fun, I used an embedded microcontroller (not an Arduino) to control a hobby servo with a Mobius action cam mounted on top and slapped the whole contraption on my car dashboard to use as a dashcam; I programmed the servo to track the angle of the steering wheel, so that the camera would point towards the direction the car was turning. It was pretty easy to do.