Protocols and data

BACnet, OPC UA, MQTT, IEC 60870 and IEC 61850, SCADA, wireless networks and data quality.

A reading is useful only when it arrives with the right time, unit and quality. These guides cover the protocols that carry it (BACnet, OPC UA, MQTT, IEC 60870 and IEC 61850) and how to keep the data trustworthy through outages.

Start with SCADA architecture for the big picture, or BACnet vs Modbus for building projects.

Networks and architecture

10 guides · about 121 minutes

  1. What is Zigbee? How the Zigbee mesh protocol works Zigbee is a low-power mesh protocol on IEEE 802.15.4: routers relay readings to a gateway's coordinator. How the mesh, Zigbee 3.0, clusters and security work. 9 min
  2. What is LoRaWAN? How LoRaWAN networks work LoRaWAN is a long-range, low-power network for battery sensors and meters. Devices, gateways, the network server, frequency plans and LoRaWAN vs NB-IoT. 10 min
  3. Zigbee vs LoRaWAN for energy monitoring: when to use each Zigbee vs LoRaWAN compared on range, data rate, power, network and cost, LoRa vs LoRaWAN, EU868 airtime limits and when an energy site needs each. 15 min
  4. What is SCADA? Architecture and energy use cases SCADA (supervisory control and data acquisition) monitors and commands remote equipment: its layers, how the architecture works, SCADA vs EMS and energy uses. 18 min
  5. Cloud API vs local gateway for energy sites Compare cloud APIs and local gateways for energy data: call quotas, timestamps, outages, control, security and hybrid sites. 9 min
  6. Over-the-air firmware updates for IoT devices Plan Zigbee OTA and LoRaWAN FUOTA updates: delivery time, image signing, failure modes, campaign checks and field verification. 10 min
  7. IoT interoperability in multi-vendor systems IoT interoperability is the ability of devices from different vendors to exchange data and use it correctly. The four types, protocol gaps and a 12-step test. 24 min
  8. IoT data privacy and GDPR compliance When IoT meter and sensor data is personal data under the GDPR, the obligations that follow article by article, and how to meet them in energy monitoring. 13 min
  9. How to set a static IP address on Windows 11 Windows 11: Settings > Network & internet > Ethernet > IP assignment > Edit > Manual. Enter the IPv4 address and subnet mask (prefix length 24), or use netsh. 6 min
  10. How to set a static IP address on Ubuntu Desktop Set a static IPv4 address on Ubuntu in Settings > Network or with nmcli (ipv4.method manual, ipv4.never-default). Check it with ip route get, then restore. 7 min

BACnet and building protocols

7 guides · about 58 minutes

  1. BACnet vs Modbus for building integration BACnet has objects, discovery and a 16-level priority array; Modbus has numbered registers and a register map. Side by side: ports 47808 and 502, MS/TP and RTU. 10 min
  2. BACnet/IP vs MS/TP BACnet/IP runs on Ethernet over UDP port 47808; MS/TP on an RS-485 bus with token passing. Compare speed, wiring, addressing, BBMDs, routers and bus capacity. 12 min
  3. BACnet objects, properties and point lists Build a BACnet point list: analog, binary and multi-state objects, Present_Value, Units, Status_Flags and the PICS. 6 min
  4. BACnet device instances, addresses and discovery A BACnet device instance is 0 to 4,194,302, unique on the site; network numbers are 1 to 65,534. How Who-Is and I-Am find devices, and why one is missing. 5 min
  5. BACnet routing, BBMDs and foreign devices A BBMD (BACnet broadcast management device) forwards Who-Is and I-Am across IP subnets. BDT entries, foreign device registration and TTL, routers and UDP 47808. 13 min
  6. BACnet COV vs polling, and data freshness BACnet COV reports a value only when it moves by the COV increment. Subscription lifetime and renewal, confirmed notifications, and when to poll instead. 8 min
  7. BACnet priority arrays and relinquish BACnet priority array: 16 levels, lowest number wins. The named levels 1, 2, 5, 6 and 8, releasing a command with NULL, and when Relinquish_Default applies. 4 min

OPC UA and MQTT

6 guides · about 67 minutes

  1. OPC UA vs MQTT vs Modbus Compare OPC UA, MQTT and Modbus: data models, status, timestamps, security, ports, one meter reading across all three and commissioning failure tests. 10 min
  2. What is MQTT? The MQTT protocol explained MQTT is a publish and subscribe protocol: clients send messages to topics on a broker, which passes them on to subscribers. Topics, QoS, ports, MQTT 5. 11 min
  3. MQTT QoS, retained messages and stale data MQTT QoS 0, 1 and 2 compared, retained messages and the retain flag, message and session expiry intervals, will delay, queue limits and stale data checks. 12 min
  4. What is MQTTS? MQTT over TLS for energy IoT MQTTS is MQTT inside a TLS connection on TCP port 8883; plain MQTT uses 1883. MQTT vs MQTTS, certificates, client identity, topic ACLs and openssl tests. 13 min
  5. OPC UA clients, servers and node identity An OPC UA NodeId is a namespace index plus a numeric, string, GUID or opaque identifier, as in ns=2;s=Tag. Client vs server, endpoint URLs and namespaces. 7 min
  6. OPC DA vs OPC UA: differences and migration OPC DA (OPC Classic) needs Windows and DCOM; OPC UA runs on any system over TCP port 4840. A comparison table, three migration routes, quality and timestamps. 14 min

IEC 60870 and IEC 61850

6 guides · about 55 minutes

  1. Choosing grid communications: IEC 101, IEC 104 and IEC 61850 Compare telecontrol, MMS, GOOSE and sampled values for RTUs, solar plants, batteries and switchgear. Define the point list and acceptance tests. 6 min
  2. IEC 60870-5-101 vs IEC 60870-5-104 IEC 104 runs on TCP port 2404 with k = 12, w = 8 and timers t0 to t3; IEC 101 uses serial FT1.2 frames. What IEC 60870-5 is, time tags and tunnels. 12 min
  3. IEC 60870 ASDUs, causes of transmission and addresses ASDU means application service data unit, the IEC 101/104 message. Tables of type IDs (1 to 103), causes of transmission and the CA and IOA address fields. 10 min
  4. IEC 60870 timestamps and quality descriptors IEC 101/104 time and quality: CP56Time2a, invalid and summer-time bits, plus overflow, blocked, substituted, not topical and invalid quality flags. 5 min
  5. IEC 60870 commands, select-before-operate and confirmation IEC 101/104 commands: direct execute, select-before-operate, activation confirmation, termination, qualifiers and checks of the real equipment state. 10 min
  6. IEC 61850: data models, MMS, GOOSE and SCL IEC 61850 MMS is client/server on TCP port 102; GOOSE and sampled values are layer-2 multicast. Logical nodes, SCL files (ICD, SCD, CID), mapping to IEC 104. 12 min

Data quality and delivery

6 guides · about 62 minutes

  1. IoT sensor data collection: methods, transport and quality How IoT sensor data is collected, transported and stored: polling and reporting, gateways, MQTT, timestamps, quality flags, stale limits and counter rollover. 18 min
  2. Telemetry timestamps, source time and arrival time Sensor timestamps: source, collection and arrival time, interval labels, time zones, clock sync, late data and duplicates in energy telemetry. 4 min
  3. Stale, missing and invalid telemetry Distinguish stale, missing, invalid and estimated sensor readings, display their status, and handle their effects on totals, charts and alarms. 11 min
  4. IoT data storage: architecture and options Compare IoT databases, edge history, replay queues and cloud archives. Size storage, define retention and verify delivery and recovery before deployment. 14 min
  5. Store-and-forward buffer sizing for edge gateways Size a gateway buffer: record rate, outage duration, bytes per record, drain time after recovery, retention limits and full-queue behaviour. 5 min
  6. Industrial polling, backpressure and retries How to budget polling on an RS-485 bus or a Modbus TCP gateway: transactions per cycle, the cost of an offline device, overdue reads and safe retries. 10 min

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