PLC interface to a PtZ camera

I am toying with the idea of controlling a Sony PTZ camera with a PLC. Its just a thought at this moment, but has anyone used a PLC serial port to tell a camera to go to specific locations on command?

I can of course use the built-in alarm ports on the camera easily enough, but there are only 4 of those and I may want more positions than that. There is an interface that is available from the surveillance system but it is costly and must be licensed. In then end I may find out that there are only 4 locations that can be stored in the camera so I may be out of luck anyway.

I'll look at this in ernest in the next couple weeks but if anyone has ever done it i would love to know what you learned.

I've done it before with Bosch and Pelco but never Sony. Shouldn't be any different though. It can be a little difficult to properly control as youll never get as accurate as a joystick. Usually calling a preposition is a little more user friendly.

Calling a preset position is just what I need to do. I can do that with the discrete inputs available, but there aren't enough of them. Its a big area to cover.

If you're using Pelco-D protocol, I can probably help you. I can give you the hex data to send for each preset that you program.

It does not appear that the Sony cameras support Pelco protocols.

http://www.vaddio.com/library?path=d&file=tc_sony_z700_commandlist.pdf

If you camera uses VISCA, here's a reference. Not sure if your model supports, but page 12 shows the commands for absolute position of the pan/tilt head.

This protocol is super simple without any checksum to calculate.

Hmm, this might not be so much of a pipe dream after all...
The Sony model I'm looking at supports Pelco-D (I don't see Visca listed) but over RS485, not 232. How did you get 485 out of a PLC? the DH port? Do you have PLC code I could look at?

I used a ML1100 with an inline 232 to 422 converter. This is the one I had: http://www.kksystems.com/inline-interface-converters/non-isolated/k2.html

Any converter similar to that would work. You need to force RTS or DTS high on the 232 side to provide power to it.

I setup the ML1100 to send ASCII strings as HEX. It takes a bit of fiddling to get the the port setup correctly with carriage returns and such. I don't have the program near me so I can't tell you exactly what I did at the moment. I didn't bother with programming the protocol into the PLC as I was only doing a dozen or so commands. What I did was figure out each command I needed to send, stored those commands in a string ST9 location and programmed buttons on my HMI to send those strings (as HEX) out the serial port. There is likely no need to receive any info from the camera, so don't bother with that. The bulk of my programming went into resetting control blocks for the AWT commands. I found that the serial port hangs very easily and resetting each AWT control block a second or so after sending the hex was the best solution. I've never had an issue since it was completed a few years ago.

Copy that. Sounds like this might work after all. Thanks.

If you're using Allen Bradley ML series, there is a prefix you need to use in your strings. Pelco D uses FFh as a beginning of message. This is not the same as FF in ASCII. I cannot find what this prefix is at the moment.

http://www.commfront.com/RS232_Examples/CCTV/Pelco_D_Pelco_P_Examples_Tutorial.HTM

This page shows the protocol. I have a program I can email you that will give you all your commands, or I can just send you the hex for whatever you want to do.

http://www.plctalk.net/qanda/showthread.php?t=68304&highlight=Eric+Hamilton

Email Eric and ask for a copy of Glass Keyboard. He was quite helpful when I was doing the same thing as you a few years ago. Glass Keyboard will show the hex for each command.

Eric is gone. [email protected] is the replacement email. Don't know how cooperative he will be yet...

If this works its really gonna tick off our CCTV guy who wants to sell me that expensive I/O interface. Can't wait.

I had a few minutes this evening and looked for this very thread:

http://www.plctalk.net/qanda/showthread.php?t=66944&highlight=hex

I don't know if you're using a ML processor, but there it is. The backslash is the magic character to use in a string to designate it as hex.

We did a movie stunt rig with a similar setup using a SoftPLC. It has a set of serial ASCII commands called COMGENIUS that makes it really easy to format the necessary strings without having to use data table or a lot of ladder logic. It also has a native 485 port.