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  1. robertjo24

    Telemetry Antenna Mounting Height

    At a minimum you should start with free space loos calculation, you can find several simple calculators online. You will need to know the frequency of the radio, distance between the master and remote radio, and the gains of both antennas. You also need to account for transmission line...
  2. robertjo24

    PLC/SCADA/TELEMETRY - Better option - Advise

    What do you mean by "ordinary wireless device"? There are industrial IO wireless links that will do what you are looking for, operating in the 902-928 unlicensed band that are not consumer grade wireless. You could install one radio at each end with yagi antennas.
  3. robertjo24

    Spare capacity on a fibre network

    In short, yes. Its done all the time. If the switches have SFP ports, I would use SFPs instead of fiber converters. If you only have copper ports available, then the fiber converters are your only real option. Now, the fiber type and converters will dictate overall speed of the link. If the...
  4. robertjo24

    Spare capacity on a fibre network

    Not really sure what you’re asking here, not enough detail provided. Are you looking to extend a LAN/L2 or a WAN/L3 connection between buildings/facilities? Is this your dark fiber, or is this coming from a service provider? Makes a difference…
  5. robertjo24

    Modbus RS-485 question

    If you have a RS-485 to 232 converter (assuming you have an RS-232 port on a PC), you can download a trial version of ModSIM. The ModSIM software will show the MODBUS communications and you can see the RTU IDs that are being polled.
  6. robertjo24

    Fiber Optic Cable Service Loop

    The NEC code would be more aligned with safety that maintainability. Look up BICSI standards regarding fiber. Service loops are always recommended. Its easier to perform one mid-span splice using a service loop than creating two splices, fitting a piece of cable.
  7. robertjo24

    Automated SCADA Functional Testing

    Are you referring to your front end polling system, or field components? If you are referring to the front end system, your best bet would be to hire a consulting company. They can review the programming and advise on CRM procedures adn compliance. A company like Enersys could help. If you are...
  8. robertjo24

    Fire Panels - replace or refurbish?

    Run this by your company's legal team. They will not hesitate to back repalcement...
  9. robertjo24

    Does Intrinsically safe circuit need to be run in cable tray or conduit?

    I cannot speak to the code, as I don’t know it verbatim, nor for your area… But, the generally accepted proper way to run cabling from a cable tray to instrumentation would be to install the cable in conduit. I don’t think anyone allows direct burring of cable, or a dangling free run...
  10. robertjo24

    UPS Input voltage

    Depends on the spec of the UPS in question. Many higher end units have the option to auto adjust to the input voltage. Others have a manual adjustable input, either through switches or strapping.
  11. robertjo24

    Access Control System and Automatic Door Operator

    A typical access control system would normally have sufficient inputs and outputs to allow for the required programming to provide door activations and inhibit signals to do what you’re looking for. I would consult a qualified access control vendor on this though, as most areas require these...
  12. robertjo24

    Yagis and phasing harness

    We have a site with a 900 MHz ISM band data radio (902-928 MHz FHSS), connected to a pair of Yagi antennas through a phasing harness. The antennas are stacked vertically as per manufacturer’s instructions to increase directional gain. What would be the result if one of the Yagi antennas were...
  13. robertjo24

    MODBUS maximum wire length

    Serial communications were never really meant to be run over controls cabling (salt & pepper). The main issues isn’t voltage drop, its line capacitance. A larger diameter cable will shorten your maximum effective communications distance. Comms links should be made via 22 or 24 AWG twisted pair...
  14. robertjo24

    CAN over T1

    Of course, if you have a true point to point T1, you can use a simple T1 Ethernet extender. It’s basically a bridging device that negates the need for a true routed network. They are available in single port and multi-port models that allow multiple devices to interconnect between sites. I...
  15. robertjo24

    CAN over T1

    I guess the first question is, are these point to point T1s? Are they full T1s or fractional T1s? Unless I’m missing something, you need a router at each site. The Westel box is usually a network interface card that allows the telco to monitor and test (loopback) the T1 remotely, more commonly...
  16. robertjo24

    Lighting arrester

    For RF lightning/surge protection devices, I recommend Polyphaser. Their site has a lot of information on the appropriate devices, proper grounding and bonding techniques, and application spec sheets...
  17. robertjo24

    20mA current loop serial data communication ?

    RS-232 current loop converters generally have 4 wires (TX+&-, and RX +&-), not three. Is it possible that in your configuration, the - lead from botht the TX & RX lines were tied together? What type of converter are you using? When links are not properly configured, they will often work over...
  18. robertjo24

    Lightning surge protection on underground and overhead network cable

    I’ve installed several of these, and we typically use either rigid metallic conduit or PVC, but always use outdoor rated (OSP) cat-5 cable. I only use the shielded Cat-5 if I’m in a high noise environment (near electrical lighting, high voltage, or variable frequency drive units). Running...
  19. robertjo24

    Twido PLC with Ethernet Cable

    If the PLC comes with a pre-configured default IP address, it should be listed in the manual. You would need to hard code an IP address on your PC to be on the same LAN as the PLC, and then direct connect to it. You will likely need to use a crossover Ethernet cable when direct connecting to the...
  20. robertjo24

    serial to ethernet encapsulation drivers

    The folks at Tactical Software have a comm port redirector package called Serial/IP that allows legacy serial based applications to make TCP/IP connections. Basically you set up the redirector on a virtual comm port, and then connect the serial application to that comm port. Here is the link, I...

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