rs-485 issues

[incentive 0]

hi have a situation..

I have 1 hikvision 96128 super nvr, 4x hikvision 16 channel encoders

 

all the analog cameras connect to the encoders and the rs-485 lines

 

so, the data on encoder one is then daisy-chained into encoder 2 data line, then 3 and so on

 

on encoder 4 it then loops back out and goes onto one cable to go around the cameras.

 

encoder 1 address = 1-16

encoder 2 address = 17=32

etc

 

the problem is, using one keyboard I can control all cameras no problems, I introduce keyboard 2 and it falls over.

 

if keyboard 1 is ptz a camera say on encoder 1 address 4 and keboard 2 then starts ptz a camera on encoder 2 address 20, encoder 2 shuts down and reboots.

 

now if I use keyboards 1 and 2 and control a camera from the same encoder at the same time say 1 and 9 all is ok

 

I think the looping of the 485 is causing a feedback issue, I need a combiner that will combine 4 inputs nd output 1,

 

but I was thinking of putting blocking diodes on the data outputs to stop any feedback causing my reboots

 

any thoughts?

[Horizon 0]

Hi incentive.

 

Do you have the 120 ohm termination resistor installed at the last camera?

Also, does the cable go from the DVR to your four encoders, then to your other cameras, stopping (terminating!) at the last camera?

It definitely isn't looped back to the DVR; it hasn't been run in a ring?

[incentive 0]

Sorted it by fitting blocking diodes on the 485 leaving the encoders

The hikvision encoders must of seen ptz commands on the line that it didnt generate and those reboots, so diodes block any commands back feeding into the encoders

 

The 485 was run from out enocder 1 to encoder 2 to encoder 3 and so on then one cable out to the cameras.