My customer has an extensive security camera system and they are under scrutiny of US Customs so everything has to be in order.We are updating his 30 camera system with 2 new 16 channel DVRs and two new 1280X1024 LCD monitors. I managed to get his old Kalatel KTD-301 PTZ controller to work and we discovered we had at least 6 PTZ cameras which hadn't been used in ages. The Kalatel is completely independent of the DVR system and works fine. The new DVRs have an RS-485 two wire interface so I want to have the additional capability of using the DVR to do PTZ. I think I only need to tie in a pair of wires from the DVR to the two-wire interface of the existing cameras. Is that a safe bet? There are only 4 wires that run the controller, 2 are for power, and I guess the other two are used for RS-485?

You should be ok, as long as the cameras are using 485, I don't recall if Kalatel uses 485 or 422. After some quick googling it appears the keyboard is RS422. You would need a converter to get the data across, I have had good luck with Sennetech code converters. What kind of DVR are you using?

Hi Jim - thanks for your help. I googled Kalatel also and wasn't able to find any manuals on the exact model. I am buying two Digimerge DHU516251's and they have a two-wire 485. The user can work the Kalatel with either DVR, but it would be nice to be able to use the built in PTZ features in the Digimerge. The DBR supports a variety of protocols, including Pelco-D, Everfocus, Pelco-P etc.