Newbie help - Rj485 connectors and generally telemetry

[jam 0]

Hello everyone,

 

I've been tasked by my boss to oversee a CCTV installation using a DM DS2 and our existing cameras at one of our buildings. As I'm an IT engineer "obviously I should know everything there is to know about CCTV"

 

Basically our CCTV engineer is on the job at the moment and were having issues. We need to connect our cameras/mounts to the DM DS2 system. The cameras work a treat but we've got some dome cameras that we will want to control and we are unable to control them because we don't have a link via the telemetry??? We have the wires coming in but we have no way of connecting them to the back of the DM DS2. We need to connect them via the RS485 port (which I'm unable to find a crimp tool for) or the serial ports which I can sort out via RS components/Maplins (electrical component superstores).

 

I know frig all about CCTV so please put it in plain dumb terms.

 

What cables will be coming in from the domes to control them and how do I get them into the back of the DMDS2 so I can use them from my desk 20 miles away from where the unit is located?

 

PS the remote dial in ect is sorted and works lovely.

 

Cheers

jam

[Soundy 1]

What model are these dome cameras? Are they PTZs (pan/tilt/zoom)? A few domes I've seen use RS485 for remote access to the OSD setup menus, but don't require it beyond the initial setup.

 

RS485 typically should not need a special connector - it uses only four wires (+/- pair each for transmit and receive), and for cameras it generally just requires a single pair (transmit pair at the controller, to the receive pair at the camera). Most cameras I've seen use some sort of screw terminals or mini plastic connectors for them; a few have wire tails you splice to.

 

The picture I found for the DS2 looks like it uses standard RJ45 jacks for its RS485 bus... as an IT guy, you should have crimpers handy for those You'd have to check the DVR's docs, but I suspect it will just use the center pins (4&5) for TX.

[Sawbones 0]

The DS2s also allow you to use the serial port connections on the back to control RS485 cameras.

 

It's pins 1 and 9.

 

I hacked up an old serial cable end when I had my DS2 installed, and simply used one of the pairs from some cat5 I'd already run. The cable can be improvised... you may be able do it with 18ga 2-conductor power wire (I tried that on a short run, and it worked). Naturally, twisted pair is better and more interference-resistant.

 

You can daisy-chain all your RS485 devices together. The trick with RS485 is assigning all the cameras their appropriate address on the bus, and terminating it at the last camera.

[jam 0]

Thanks for that guys. I have got an Rj45 crimp tool in my arsenal so why my CCTV engineer didn't just ask me to bring mine into work is beyond me. I honestly don't think he knows which is a little concerning. I would like to keep the serial ports free as from what I read in the instructions they can be used to trigger other events and this may work well as we have an automated gate were currently having issues with so I may interface the 2 together so when the camera is activated by motion the gates open and the doors unlock. But I'll get into more of that later when I have finished figuring out these systems.

 

I have read the manual and the RS485 use a TX+ and a TX-. How do I terminate them, I think theres the setting in the firmware of the DS? Is that how I terminate it?

 

The cameras are a mixture of dome, PTZ and statics. (12 cameras in total).

Thanks in advance

jam

[Soundy 1]

Sawbones: Pins 1 and 9?? That's kinda odd... standard DB9 serial ports on a PC, pin 5 is ground and 3 is TX. You sure about that?

 

(Side note of general interest: http://www.pinouts.ru is one of the greatest unsung resources on the 'net )

 

jam: from looking at the external pics of that unit, it looks like it has a number of different output methods that might work better with the gate, including a least a couple of dry-contact relays. Unless you have a gate controller with RS-232/422/485 inputs, I don't think you'd be able to activate them off a serial port (at least, assuming these ARE standard RS-232 serial ports).

 

RS-485 labels the transmit connections TX+ and TX-... on the camera, you probably want to use the RX+ and RX- (although I have seen a few that label them TX as well, probably trying to tell you what you want to connect those terminals to on the other end???). Some will alternately call them TX(A) and TX(B).

 

Termination on the cameras will most often be a small switch (DIP switch or similar) that terminates the end of the line with a resistor. You would only do this on the last camera in the chain though. You SHOULD be able to wire the cameras in a star topology as well - it's usually a lot easier, since all the cameras' video wiring is home-run as well and you'll usually pull the signal along with the video. Although it's not technically a daisy-chain, the end result is that the cameras are all in parallel, and it will usually work just fine.

 

As for triggering the gates from the camera, that can be tricky... you don't want, say, a stray cat wandering through the frame, or a moth flitting past, to trigger your gates to open and doors to unlock. It could be useful the other way, though, whereby someone opening the gates (keypad? swipe card?) triggers the DVR to switch to a higher resolution/framerate on the gate camera, for a clearer picture of who's entering... stuff like that

[Sawbones 0]

Pretty sure, Soundy. The DS2 has four serial ports on the back, and #3 and #4 can be used for RS-485 telemetry (the first two don't do RS-485, only RS-232). Serial ports 3&4 use pin #1 for TX+ and Pin #9 for TX-

 

Page 21 in this PDF shows the pin-out:

 

http://dedicatedmicros.icentera.com/exLink.asp?5971824OA71K75I27147120

[Soundy 1]

Pretty sure, Soundy. The DS2 has four serial ports on the back, and #3 and #4 can be used for RS-485 telemetry (the first two don't do RS-485, only RS-232). Serial ports 3&4 use pin #1 for TX+ and Pin #9 for TX-

 

Page 21 in this PDF shows the pin-out:

 

http://dedicatedmicros.icentera.com/exLink.asp?5971824OA71K75I27147120

 

Ahhh, got it... okay, so they're using a slightly non-standard (as far as "DB9 serial" goes) pin configuration - pin 1 would normally be Carrier Detect and pin 9 would be Ring Indicator, but those wouldn't be needed here as there's no modem support.

 

Good to know!

[jam 0]

OK well here we go.

 

First problem I encountered is that the RS485 port is an odd port I've never seen before certainly not an RJ45 plug nor an RJ11. So binned that idea as I think it may have been made bespoke to DM stuff making you buy more DM stuff.

 

Second problem serial port (DB9 male). After searching I found a plug (currently on another lead) unsoldered it and got it ready to use. Our system however only has 2 DB9 ports as opposed to the manual which states there should be 4. Called DM who then tell me to use the green bus adapter and treat it as a serial port connection for the unit.

 

Third problem. Protocols. The protocols on the cameras were wrong and were adjsuted to Pelco-P now.

 

Fourth problem. ID's. The camera ID's were all wrong. Re-ID'd them.

 

Fifth problem. Wiring. It was all wrong. Instead of being a typical bus system they had wired it in parallel. This obviously didn't work and it took me showing the CCTV engineer the wiring issue by running a fresh cable straight from one camera to the DVR unit and show it working.

 

So now we have him re-wiring the cameras to how they should be wired not how he wants them wired. To be honest I'm wondering what exactly were paying him for as he's done nothing but argue with me and I've been right everytime. This venture into world of CCTV is great I'm really enjoying it. The 'CCTV engineer'is really getting on my nerves though, as were paying for the priviledge of him argueing with me.

[jam 0]

My next issue is the hard drive. Its currently running a 80GB HDD with 16 cameras blazing at it constantly its not lasting very long and I don't want to reduce the PPS. So as I'm an IT Engineer I'm going to replace it myself. However has anybody tried putting the new and old HDD into a computer and running Norton Ghost and seeing if it works? It doesn't matter if it doesn't but just wondering as this could save alot of hassle.

 

Cheers

jam

[Sawbones 0]

My next issue is the hard drive. Its currently running a 80GB HDD with 16 cameras blazing at it constantly its not lasting very long and I don't want to reduce the PPS. So as I'm an IT Engineer I'm going to replace it myself. However has anybody tried putting the new and old HDD into a computer and running Norton Ghost and seeing if it works? It doesn't matter if it doesn't but just wondering as this could save alot of hassle.

 

Cheers

jam

 

Yes... changing out the hard drives on SOME dm units can be done. I actually did mine (went from 80GB to dual-300GB drives... a huge improvement), but it took a bit of trial and error (and a firmware update) to make it all work right.

 

I'm pretty sure there are instructions in these forums on how to make the switch... do a search and see if you can find it.

[Cyberprog 0]

Appologies for dragging up an old thread here, but I'm in a similar situation.

The connections that DM uses that look like RJ11 *are not* RJ11. They are DEC MMJ Connections. CPC Sell a crimp die set for these, as well as the crimp jacks themselves.

My units are DS2A's without the CD, and only have a single Serial Port along with the twin MMJ RS485 Bus option.

Inside, both units have a board connected to what is probably the second serial port marked RSTCA. One unit has this connected to the serial port, the other does not, but it looks like it's a simple case of shifting one to the other if needed.

My 9-Channel unit doesn't have space for a second Serial Port, but the 16-Channel does. Both are DVTR units with the latest firmware installed from the DM Website (As they've had new disks).

Does anyone have any advice on which serial port or bus things should be connected to?