Multiple PTZ cameras RS-485 cabling

[tgmagic 0]

First post here and have a few questions

 

I am looking to upgrade 3 of my 6 analog dome cameras to PTZ domes.

Currently each camera has Siamese RG59 cable w/power.

 

I will be purchasing a joystick and 3 PTZ domes, both supporting RS-485 for control.

Nearest camera to be replaced is about 30M away from the DVR and furthest is 60m.

Each camera is about 15m from the other.

 

My questions:

 

1) What cable I should use for adding PTZ control.

 

My original thoughts were to run CAT5e (I have a couple of half boxes spare) but after doing some investigating it seemed like some people had issues with RS-485 over CAT5e and warned not to use it.

 

2) Will I need to get a cable from each camera back the joystick/DVR or do I run a cable from one camera to the next? (I don't mind either)

 

3) Is it possible to use both a joystick and the DVR to control the PTZ or is limited to one controller over RS-485?

 

Any help/advice is appreciated.

[Securame 0]

My questions:

 

1) What cable I should use for adding PTZ control.

 

My original thoughts were to run CAT5e (I have a couple of half boxes spare) but after doing some investigating it seemed like some people had issues with RS-485 over CAT5e and warned not to use it.

 

2) Will I need to get a cable from each camera back the joystick/DVR or do I run a cable from one camera to the next? (I don't mind either)

 

3) Is it possible to use both a joystick and the DVR to control the PTZ or is limited to one controller over RS-485?

 

Any help/advice is appreciated.

 

1) Cat5e should work. You just need two wires for RS485.

2) You can do it both ways. From DVR to each PTZ; or from DVR to PTZ#1, from PTZ#1 to PTZ#2, and from PTZ#2 to PTZ#3.

3) Yes, you can control the PTZs at the same time from both the joystick and the DVR.

[survtech 0]

CAT5e or CAT6 will transport control signals up to 4,000 feet using RS422/485. You also have the advantage that if you later want to replace the analog cameras with IP, you will already have the cabling in place. I would make sure to pull some extra slack so that you have enough to put an RJ45 on each end when replacing the cameras with IP.

 

When you wire the PTZs control lines, transmit (Tx) on the DVR side connects to receive (RX) on the PTZ side. + to + and - to -. By the way, if your DVR only has one RS422/485 output it is not recommended to "T" off multiple lines. There are products that "split" the signals. GE Security makes a KTD-83 "Data Signal Distributor" which will connect up to 5 devices to one port. Their KTD83-16 splits data to up to 16 devices. Pricing is in the $130-140 range for the KTD-83 and around $220 for the KTD83-16.

[Securame 0]

By the way, if your DVR only has one RS422/485 output it is not recommended to "T" off multiple lines. There are products that "split" the signals. GE Security makes a KTD-83 "Data Signal Distributor" which will connect up to 5 devices to one port. Their KTD83-16 splits data to up to 16 devices. Pricing is in the $130-140 range for the KTD-83 and around $220 for the KTD83-16.

 

Why would that recommendation be? Because the signal might not be strong enough if connection many RS485 cables on the DVR side? I have done this before a few times, and never had any problem, without using any data distributor.

[survtech 0]

Why would that recommendation be? Because the signal might not be strong enough if connection many RS485 cables on the DVR side? I have done this before a few times, and never had any problem, without using any data distributor.

No, because just tying multiple runs together introduces an impedance mismatch at the DVR. Data pulses can travel back down the cable and reflect around it, causing weird effects like the PTZs not obeying commands, executing the wrong commands or multiple PTZs moving simultaneously.

 

Yeah, sometimes you can get away with it but the first time a system acts up, you'll probably spend hours trying to troubleshoot the problems.

[tgmagic 0]

Thanks for the replies.

Both the DVR and the Joystick do only have a single RS-485 connection

I live in the UK and can't seem to find any the Data Signal Distributors as suggested.

 

If I decide to go from camera to camera would I still need the distributor?

[cctvmann 0]

ive always used beldon screened for any transmission.

http://www.fastflex.co.uk/100m-8723-lsf-equivalent-cable-2-pair-22awg-482-p.asp

[ilk 0]

Thanks for the replies.

Both the DVR and the Joystick do only have a single RS-485 connection

I live in the UK and can't seem to find any the Data Signal Distributors as suggested.

 

If I decide to go from camera to camera would I still need the distributor?

 

 

In the UK you can buy these from trade distributors manufactured by BBV and Pelco.

 

Ilkie

[SunnyKim 2]

One question, gentlemen.

From my curiosity, how do you guys handle against lightening and thunder? The induced current would be extremely high over a thin -long RS-485 line, damaging all electronic devices attached to it.

[ilk 0]

One question, gentlemen.

From my curiosity, how do you guys handle against lightening and thunder? The induced current would be extremely high over a thin -long RS-485 line, damaging all electronic devices attached to it.

 

If running data cabling from external cameras (including twisted pair, coax and computer networking) the first point of contact with the system should be via lightning/surge arrestors such as manufactured by companies such as Furse (see http://www.furse.com/pub/en/electronic-system-protection.

 

Regards

 

Ilkie

[tgmagic 0]

Thanks again for the responses.

So am I right in thinking that is I use 'Star' wiring I will need a distributor and if I 'Daisy Chain' from one camera to the next I wouldn't need a distributor?

 

I couldn't find anyone selling BBV/Pelco distributor. I did however find a few places selling this particular product - Genie RS004 - http://geniecctv.com/product/data-transmission-3/

Would this work for 3 cameras/2 controllers?

 

Should I forget the CAT5e and and go with the Belden screened? Will this be more reliable?

 

Thanks

[cctvmann 0]

Thanks again for the responses.

So am I right in thinking that is I use 'Star' wiring I will need a distributor and if I 'Daisy Chain' from one camera to the next I wouldn't need a distributor?

 

I couldn't find anyone selling BBV/Pelco distributor. I did however find a few places selling this particular product - Genie RS004 - http://geniecctv.com/product/data-transmission-3/

Would this work for 3 cameras/2 controllers?

 

Should I forget the CAT5e and and go with the Belden screened? Will this be more reliable?

 

Thanks

id go beldon myself as the cable is screened bear in mind un screened cable will not block intereferance from outside areas

[survtech 0]

Thanks for the replies.

Both the DVR and the Joystick do only have a single RS-485 connection

I live in the UK and can't seem to find any the Data Signal Distributors as suggested.

 

If I decide to go from camera to camera would I still need the distributor?

If you daisy chain the PTZs, you don't need a code distributor. Daisy chaining means one run of wire loops from camera-to-camera. In that case, you can run one long CATx cable and either have the run loop in and back out from each PTZ or have up to 2 meter "stubs" off the main line to each PTZ.

 

In that case, best practice is to turn off the termination at every PTZ except the last one in the chain. I have left termination "On" on each PTZ in a 3-PTZ daisy chain and control still works but that depends on the circuitry at the transmitter end. Impedance will be low in that case.

 

Impedance is easy to calculate when running terminations in parallel: just divide the number of devices by the resistance of each termination. PTZ termination is 100 ohms, so the impedance is the invert of n/100 where n=the number of devices in a chain. Two devices daisy chained is 2/100 or 1/50 = 50 ohms. Three devices is 3/100 or 1/33 = 33 ohms. Etc. 100 ohms is optimum but RS422/485 is not that critical of end termination impedance with most equipment.

 

For that matter, cable type isn't that critical for PTZ control either. I've used 22/2 shielded, CAT5, even zip cord. CATx can transport RS422/485 signals up to 4000 feet. Other cable types may have reduced transport distance but not that reduced.