rs-485 combined

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?

If the keyboard is a standard PC keyboard, I'd just get a dual view KVM switch and then you can use two keyboards simultaneously via the KVM switch.

Should be a termination switch on the keyboards. It should be on with the keyboard at the end of the chain and off with the keyboard not at the end of the chain. The keyboards have to be addressed too.

Should be a termination switch on the keyboards. It should be on with the keyboard at the end of the chain and off with the keyboard not at the end of the chain. The keyboards have to be addressed too.

Are they the Hikvision 1003ki keyboard? I believe the 2nd keyboard ta and tb should be connected the the 1st keyboard ra and rb, or are they just wired all in parallel?

Hi the keyboards are the 1100 ip touchscreen keyboards so there is no direct 485 cable from these.

485 from the encoders only all parraled up...

I tried my idea and it works..the encoders obv dont like it when it sees data transmitted that wasnt from its own encoder data line..blocking diodes on the a b line done the trick

And the ip keyboards are practlically useless without a decoder..as it doesnt recognise any nvr video output