Glossary
IoT Protocol Glossary
Plain definitions of the terms you meet on every mixed-protocol site.
A
- AS923
- The LoRaWAN regional parameter plan used in Malaysia and several other Asia-Pacific countries. Gateways and devices must support it. LoRa Integration
B
- BACnet/IP
- BACnet carried over IP networks, normally on UDP port 47808. It is the common transport for modern building controllers. BACnet Integration
- BACnet/SC
- BACnet Secure Connect. A transport that adds encrypted, authenticated connections to BACnet networks. BACnet Integration
- BLE advertising
- A Bluetooth Low Energy device broadcasting small packets that any nearby scanner can hear, without a connection. BLE Integration
C
- Class A, B and C
- The three LoRaWAN device classes. Class A listens only after it transmits, Class B adds scheduled listening windows, and Class C listens almost continuously. LoRa Integration
- Coil
- A single-bit read and write value in the Modbus data model, usually an output such as a relay. Modbus Integration
- COV
- Change of value. A BACnet service where a device notifies subscribers when a point changes, instead of being polled. BACnet Integration
D
- Datapoint type (DPT)
- The KNX definition of how the bytes of a group address are interpreted, such as DPT 9.001 for a two-byte temperature. KNX Integration
- DIN rail
- A standard metal rail used to mount industrial devices inside electrical cabinets.
E
- Edge gateway
- A device or computer at the site that runs protocol drivers and forwards normalized data upstream.
- ETS
- The Engineering Tool Software used to design and commission KNX installations. Its project export holds group address names and types. KNX Integration
G
- GATT
- The Generic Attribute Profile used by connected Bluetooth Low Energy devices to expose services and characteristics. BLE Integration
- Group address
- The KNX identifier, such as 1/2/5, that devices send telegrams to. It has no meaning without the ETS project. KNX Integration
H
- Historian
- A store that records tag values over time so they can be trended, queried and exported.
- Holding register
- A 16-bit read and write value in the Modbus data model. Most configuration and measurement values live here. Modbus Integration
K
- KNX IP tunnelling
- A connection method that lets software talk to a KNX bus through a KNX IP interface. Each interface supports a limited number of tunnels. KNX Integration
L
- Last Will
- An MQTT feature where a broker publishes a stored message if a client disconnects unexpectedly. MQTT Integration
- LoRaWAN
- The network protocol, defined by the LoRa Alliance, that runs on LoRa radio. Devices send uplinks that gateways forward to a network server. LoRa Integration
M
- MQTT broker
- The server that receives MQTT messages and delivers them to subscribers of the matching topics. MQTT Integration
- MS/TP
- Master-Slave/Token-Passing. A BACnet data link that runs on shared RS-485 wiring. BACnet Integration
O
- OTAA
- Over-the-air activation. The preferred way for a LoRaWAN device to join a network, using keys that produce fresh session keys. LoRa Integration
P
- Present value
- The most important property of a BACnet object: its current reading or state. BACnet Integration
- Priority array
- A 16-level structure on commandable BACnet objects that decides which write wins and lets one level be released cleanly. BACnet Integration
Q
- QoS
- Quality of Service in MQTT. QoS 0 is at most once, QoS 1 at least once and QoS 2 exactly once. MQTT Integration
- Quality flag
- A marker stored with a tag value that says whether the reading is good, stale or failed.
R
- Retained message
- An MQTT message the broker stores and delivers immediately to any new subscriber of the topic. MQTT Integration
- RS-485
- A serial electrical standard for multi-drop wiring over long distances. It underlies Modbus RTU and BACnet MS/TP. Modbus Integration
- RSSI and SNR
- Received signal strength and signal-to-noise ratio. Measures of how well a gateway hears a radio device. LoRa Integration
S
- Sparkplug B
- A specification that defines topic names and payloads for industrial data on top of MQTT. MQTT Integration
- Store and forward
- Holding data at the site during an outage and sending it in order when the connection returns.
T
- Tag
- A single named, typed data point in IoTServa, with a unit, timestamp and quality flag.
W
- Who-Is and I-Am
- The BACnet discovery services. A Who-Is asks devices to identify themselves and each answers with an I-Am. BACnet Integration
- Word order
- In Modbus, which of the registers that make up a larger value holds the high word. Devices differ. Modbus Integration
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