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About jakerjaker

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  1. I'm wondering if anyone has advice on security for a remote SCADA system that will be accessed over the internet via DSL connection (static IP). Specifically, I'm wondering if certain PLCs and associated HMI software are considered more secure. I met with an AB rep who mentioned that Wonderware was now considered vulnerable while RSView\RSLinx was not. From looking around it seems like this might just be some salesmanship on his part, but I was wondering what people thought. Is a router with firewall and VPN capability in front of PLC sufficient security? Are there PLCs with built in firewall/VPN capability? Do people use point to point connection services (I imagine this is costly)? Any other considerations I'm missing? Thanks.
  2. Best PLC/PAC for small remote SCADA system

    Good points. I will likely have a router/hub and I hadn't thought of using all DC digital I/O with relays. Of course I still need the analog inputs which seem to be the most costly. I am considering going the AB Micrologix or Compactlogix route after meeting with a good local rep. I don't yet know the cost of an AB system though. I imagine quite a bit more than Opto22 or Omron.
  3. Hi all, I'm a newbie to the forum and to PLCs in general so forgive me if this is covered elsewhere and if I get some facts wrong. I am looking at outfitting a few remote sites with SCADA systems for remote control of sluice and crest gates. The gate actuators have fairly simple control schemes (120VAC and 24VDC loops to "raise" and "lower" coils/solenoids) so my I/O is fairly small. These SCADA systems will be accessed through VPN via the internet (any suggestions on security for this type of remote access is welcome too). I was wondering what people would suggest for a fairly small inexpensive system. I have been looking at the Opto22 SNAP PAC controller as a possibility. In theory I like the higher level functional block diagram programming because, for one, I've never programmed ladder logic but it seems fairly limited and focused on discrete relay inputs to me (I'm sure I'll get myself into trouble on this one). For example, I'd like to be able to do slightly more complicated control loops for setting flows/gate setpoints. This would involve constant monitoring of position sensors and River stage/flow sensors. I'm sure this is possible in LL it just seems a little more straightforward to me in FBD. Admittedly I come from a high level programming background. If people have LL vs. FBD experience I'd love to here about it. I can see how the higher level FBD could get you into trouble as simpler is better right? Anyway, here is what I believe I need for I/O and comm for each site. (3) 120VAC digital inputs (sense 120VAC common from actuator in remote control) (6) 120VAC digital outputs isolated (routes 120VAC common from actuator back to raise or lower coil) (5) 4-20mA analog inputs (position sensors from actuators and overcrest inclinometers) (1) 24VDC digital input (sense 24VDC common from overcrest gate) (2) 24VDC digital outputs (routes 24VDC common to raise or lower solenoid) (9) analog voltage inputs w/ completion resistors for 20A CTs (for monitoring current draw on (3) 3-phase motors) (2) analog voltage inputs w/ completion resistors for 200A CTs (for monitoring current draw on (1) dual leg 240VAC motor) (2) ethernet 10/100 Mbps (need to connect to VPN router/DSL modem as well as to an existing Datalogger to retreive other parameters such as Lake and River levels) (1) RS-232 serial (potentially for adding backup dialup modem access) Any suggestions and advice for a small remote system like this would be much appreciated. Thanks!