SCADA does not “read the PLC.” It reads specific memory locations inside the PLC, over a network, using a protocol both sides agree on, on a schedule the SCADA engine controls. Every screen value, every alarm, every trend point comes from that one loop: ask, answer, map, display. Most explanations stop at a list of protocol names. That… Read More: How Does SCADA Communicate With a PLC? Explained Simply »
Putting LonWorks on an IP network sounds like the easy part. The protocol doesn’t change, and Ethernet is already in the building. Then a device stops forwarding and nothing in the LonWorks tooling explains why. ISO/IEC 14908-4 doesn’t rewrite LonTalk into a different application protocol. It transports LonTalk packets over IP using a mechanism it calls CNP/IP. But… Read More: LonTalk over IP (IP-852): Setup and Troubleshooting »
The first thing to understand about transparent mode is that there is no fixed control word bit layout to memorize. The information is not hidden. Under ABB Drives or PROFIdrive, the profile defines how the control word, status word, references and actual values are interpreted. Under Transparent 16 or Transparent 32, the FPBA-01 does not impose that interpretation.… Read More: ACS880 PROFIBUS Transparent Mode: Control and Status Words »
Two profiles. The same drive can use either one over the same network. Even when the configured process-data size is identical, the meaning of the words can change. That is what makes this comparison worth writing down. Nothing visibly breaks when you pick the wrong one. The bus goes green, the PLC exchanges data, the drive accepts a… Read More: PROFIdrive vs ABB Drives Profile: Key Differences »
One parameter decides how your PLC talks to an ACS880 over PROFIBUS. It is 51.05 Profile. Not 51.02. That one is the node address, and it gets confused with the profile setting constantly — including in some vendor quick-start guides that use the label “Protocol/Profile” for 51.02. On an ACS880 with an FPBA-01, node address is 51.02 and… Read More: ACS880 PROFIBUS DP Profiles: How to Choose the Right 51.05… »
Most comparisons of these two treat them as rivals picking a fight over the same job. That framing gets the engineering wrong, and it gets one important fact wrong too. BACnet defines LonTalk as one of its own data link layers. Clause 11 of the BACnet standard specifies how BACnet messages ride on the LonTalk protocol. They are… Read More: LonWorks vs BACnet: How the Two Data Models Differ »
The power line channel is the one that fails for reasons nobody wrote down. A surge arrester goes in on the same board. A lighting retrofit lands on the same circuit. Both are perfectly good electrical work, and both can take the network down. ISO/IEC 14908-3 is unusually direct about this. It declines to specify the medium at… Read More: LonWorks Power Line: The 125-140 kHz Channel Explained »
Free topology is the reason people put up with LonWorks wiring. Bus, star, loop, or any mix of them, on one pair, with one termination you can put anywhere. No daisy-chain discipline, no polarity to get right. It isn’t free of rules. It has distance limits, a termination that has to be the right value, and a power… Read More: LonWorks Twisted Pair Wiring: Distances and Link Power »
A Modbus register is sixteen bits and nothing else. What those bits mean lives in a document somebody emailed you. A LonWorks network variable carries its own type. Two devices that agree on the type exchange a temperature without anyone deciding whether it’s tenths of a degree. That difference is the reason the protocol exists, and it’s also… Read More: LonWorks Network Variables: Selectors, Bindings and Polls »
Pick the wrong service type and the network still works — until it doesn’t. Under light load everything delivers. Under load, the acknowledged multicast you specified starts eating the channel it needs, and the symptom looks like a hardware fault. ISO/IEC 14908-1 gives you four services. This is what each one actually does on the wire, when to… Read More: LonTalk Service Types: Which One to Use and Why »