Industrial Networking & Communications Glossary
Industrial Ethernet, cellular and radio telemetry links, network hardware, and the communications layer under SCADA. 107 terms in this topic - each defined in plain English on its own page.
Below every protocol is a physical link, and for remote operations the link is often the hardest part of the job. This topic defines the industrial networking layer - Ethernet, switches, and network resilience on the plant side; cellular, radio, and satellite telemetry on the remote side - plus the RF and link-budget vocabulary that determines whether a far site stays connected. Protocol-level terms live in Industrial Protocols; this is the layer beneath them.
107 Terms
What is 802.1AS gPTP in time-sensitive networking?
The TSN time-sync profile that elects a grandmaster clock and shares one time base so scheduled and IT traffic converge.
Read → GlossaryHow do you aim a directional antenna using RSSI?
Pre-point on bearing, sweep for the main-lobe peak, dodge side lobes, and lock the mount without losing the aim, then verify on the trend.
Read → GlossaryHow do you aim a directional cellular antenna?
Sweep slowly while watching RSRP and RSRQ, peak on the stable reading, confirm the main lobe, then lock and reconfirm.
Read → GlossaryWhat Is an APN?
Access Point Name - how public vs private APNs route cellular SCADA traffic - explained.
Read → GlossaryWhat Is Cellular Band Locking on a Remote Gateway?
Forcing a modem onto one LTE band or tower to stop it hopping between weak cells and dropping the link.
Read → GlossaryWhat Is Bandwidth Throttling?
Deliberate rate limiting - carrier-imposed vs operator-imposed - and how QoS keeps critical SCADA traffic moving.
Read → GlossaryWhat is a broadcast storm in an OT network?
A runaway flood of looping frames that can knock a flat control network offline; stopped by storm-control and loop prevention.
Read → GlossaryHow do you budget antenna cable loss?
Add cable and connector loss, subtract from antenna gain, and confirm the net clears your signal margin with room to spare.
Read → GlossaryHow do you calculate an RF link budget by hand?
Sum transmit power, gains, and losses in dB, subtract free-space path loss, and check received level against receiver sensitivity for margin.
Read → GlossaryWhat Is Carrier Aggregation in Cellular Telemetry?
How LTE-Advanced bonds multiple bands to lift a remote gateway's throughput for historian sync and firmware pushes.
Read → GlossaryWhat is a cell/area zone in an industrial network?
The lowest control segment holding a machine's PLC, I/O, and HMI, how zones connect, and why cells contain faults.
Read → GlossaryWhat Is Cellular Failover?
How a remote site auto-switches to a backup link when the primary drops - active vs passive and dual-carrier designs.
Read → GlossaryWhat Is a Cellular Gateway?
The industrial 4G/5G router that connects remote RTUs, PLCs, and flow computers to SCADA - explained.
Read → GlossaryWhat Is a Cellular Modem?
The LTE/5G radio inside every cellular gateway - generations, bands, and modem vs gateway - explained.
Read → GlossaryWhat Is Cellular Signal (RSSI)?
Cellular signal strength in dBm, and how RSSI compares to RSRP, RSRQ, and SINR on LTE - explained.
Read → GlossaryCellular vs Satellite vs Radio Telemetry
Coverage, latency, bandwidth, and cost of the three remote SCADA backhauls, and how to choose - compared.
Read → GlossaryHow do you place a cellular antenna at a remote site?
Pick omni or directional from the survey, mount high and clear of steel, orient to the signal, and confirm the live numbers.
Read → GlossaryHow do you choose between licensed and unlicensed radio?
Weigh interference protection, range, deployment speed, and congestion risk against data criticality to pick the radio class per link.
Read → GlossaryHow do I choose a network topology for a SCADA system?
A decision guide weighing star, ring, bus, and mesh against cost, distance, fault tolerance, and site layout.
Read → GlossaryWhat is CIP QoS?
DSCP marking plus switch priority queues that serve time-critical EtherNet/IP I/O ahead of ordinary traffic.
Read → GlossaryHow do you commission a cellular SCADA gateway?
Verify power, signal, and SIM in order, prove the host path and recovery, then record the baseline and confirm hardening.
Read → GlossaryHow do you commission a point-to-multipoint radio network?
Verify the master first, add remotes one at a time on unique addresses, tune poll pacing and timeouts, and prove every site answers each cycle.
Read → GlossaryWhat is a control network in a DCS?
The dedicated, deterministic, redundant tier linking DCS controllers, I/O, and stations, kept separate from business IT.
Read → GlossaryWhat is a daisy-chain topology in an industrial network?
Linear device-to-device wiring via two-port switches, its cabling savings, cascade risk, and how it becomes a ring.
Read → GlossaryWhat is a data plan overage on a SCADA SIM?
How a chatty poll rate or stuck retry loop blows past a pooled-data cap, and how to budget bytes per site.
Read → GlossaryWhat Is a Default Gateway in a SCADA Network?
The router address a device uses to reach off-subnet destinations, why a wrong gateway lets a PLC ping locally but never reach the cloud, and how it fits the cellular router at a remote pad.
Read → GlossaryWhat is a Deny-by-Default Firewall Rule?
Configuring OT firewalls to block everything and permit only named, justified flows so segmentation actually holds.
Read → GlossaryWhy does my cellular SCADA gateway keep dropping offline?
Triage RSRP/RSRQ signal, APN and SIM issues, data caps, carrier band drops, and a watchdog reboot loop.
Read → GlossaryHow do you diagnose high latency on a cellular link?
Confirm it is latency not a drop, localize the delay to radio, path, or host, check RSRQ for congestion, and read the jitter.
Read → GlossaryHow do you diagnose radio dropouts that track the weather?
Correlate outages to rain, wind, and temperature first, then trace thin fade margin, coax water ingress, flexing mounts, or ducting.
Read → GlossaryWhat is deep packet inspection of industrial protocols?
Reading past the TCP header into Modbus, DNP3 and EtherNet/IP payloads to see function codes and setpoint changes.
Read → GlossaryWhat Is Dual-SIM?
Two carrier SIMs in one modem with automatic switchover - carrier redundancy for remote sites, explained.
Read → GlossaryWhat is dynamic DNS for remote sites?
Keeping a stable hostname pointed at a gateway whose public IP changes, and why a fixed-IP SIM is often preferred.
Read → GlossaryWhat Is an Edge Router?
The boundary device that connects a remote site to the WAN and handles NAT, firewall, VPN, and failover - explained.
Read → GlossaryHow do you estimate a site's monthly cellular data?
Scale bytes per poll to a month, apply overhead, add non-poll traffic, add margin, and size the plan to the total.
Read → GlossaryWhat is a failover hold-down timer in dual-SIM failover?
The dwell time that stops dual-SIM or dual-WAN failover from flapping back and forth on a marginal link.
Read → GlossaryHow do you fix a duplicate IP address?
Read the conflict indication, find the two MACs by ARP or switch table, isolate the interloper, reassign, and prevent recurrence.
Read → GlossaryWhat is a flat network and why is it risky in OT?
An unsegmented OT network where every device reaches every other, letting malware and broadcast storms spread unchecked.
Read → GlossaryWhy is the network status LED flickering?
Read the flash code, separate a link problem from a connection timeout, and trace it to cable, RPI, or a duplicate IP.
Read → GlossaryWhat is full packet capture and PCAP retention in OT?
Recording every packet to a rolling PCAP store for forensic replay, and the storage-versus-rewind trade-off.
Read → GlossaryWhat is gateway uplink payload batching?
Coalescing many readings into one larger message to amortize per-message overhead, with a batch-window latency tradeoff.
Read → GlossaryWhat is gear mesh frequency analysis?
Reading the tooth-mesh frequency and its sidebands to diagnose gear wear, eccentricity, and a cracked tooth.
Read → GlossaryWhat Is Half-Duplex vs Full-Duplex?
One direction at a time vs simultaneous, and how turnaround delays limit polling on RS-485 and radios.
Read → GlossaryHow do you harden a cellular gateway config?
Change defaults, close unused ports, keep the SIM on a private APN, lock remote management, and baseline the config.
Read → GlossaryWhat Is a HART Multiplexer?
The panel device that pulls digital HART data off many 4-20 mA loops for asset management.
Read → GlossaryWhat is a HART signal repeater?
A device that regenerates a weak HART digital signal on long or high-capacitance cable runs.
Read → GlossaryWhat is a hub-and-spoke topology in a SCADA network?
One central SCADA host polling many dispersed remote sites over radio, cellular, or VPN, with bandwidth and single-hub risks.
Read → GlossaryWhat is IGMP snooping in a SCADA network?
A switch feature that delivers multicast only to subscribers, stopping the floods that cause EtherNet/IP I/O timeouts.
Read → GlossaryWhat Is an Industrial Ethernet Switch?
The hardened DIN-rail switch that ties field PLCs and RTUs together - managed vs unmanaged, explained.
Read → GlossaryWhat Is ISA-100 Wireless?
The ISA100.11a industrial wireless standard: secure self-healing mesh for field instruments, and how it compares to WirelessHART.
Read → GlossaryWhat Is Jitter?
Variation in packet delay, why it differs from latency, and how it disrupts polling on wireless SCADA links.
Read → GlossaryWhat Is Latency?
Network delay in SCADA, how transports compare, and why it matters for polling and remote control - explained.
Read → GlossaryWhat is a latency budget for remote control?
Allocating a total end-to-end delay allowance across the path to decide if closed-loop control over cellular is safe.
Read → GlossaryWhat Is Line of Sight and the Fresnel Zone?
Why a clear view is not enough and how the Fresnel zone and earth curvature set antenna height.
Read → GlossaryHow do you lock cellular bands on a gateway?
Survey to find the strongest stable band, lock the modem to it to stop hunting, and verify the link holds and recovers.
Read → GlossaryWhat Is LoRaWAN?
The low-power, long-range LPWAN for battery sensors, its data-rate limits, and where it fits monitoring - explained.
Read → GlossaryWhat Is the LoRaWAN Duty Cycle Limit?
The regulatory cap on sub-GHz airtime that limits reporting frequency and downlink, and how it shapes payload sizing.
Read → GlossaryWhat is LPWAN uplink versus downlink asymmetry?
Why LPWAN favours telemetry uplink and limits downlink, making it poor for fast remote control.
Read → GlossaryWhat Is LTE Cat-M1?
The mobility-capable, higher-throughput cellular IoT tier, when to pick it over NB-IoT, and its role in RTU telemetry.
Read → GlossaryWhat is the difference between a managed and unmanaged industrial switch?
Unmanaged switches just forward traffic; managed switches add VLANs, ring redundancy, port security, and diagnostics.
Read → GlossaryHow do you measure cellular latency and throughput?
Baseline round-trip time and jitter to your host, baseline data rate, capture the variation, and match the polling design.
Read → GlossaryWhat Is a Media Converter?
The device that bridges copper Ethernet to fiber for distance and noise immunity - and how it differs from a switch.
Read → GlossaryWhat is a mesh topology in an industrial network?
Nodes that relay for each other for self-healing multipath resilience, and where wireless mesh like WirelessHART fits.
Read → GlossaryWhat is MQTT maximum packet size?
The MQTT 5 property that caps how large a packet the broker may send a constrained client, protecting a small receive buffer from an oversized payload.
Read → GlossaryMulticast vs unicast I/O on EtherNet/IP
One packet to a group versus a copy per consumer - the switch-load trade-off behind EtherNet/IP I/O delivery.
Read → GlossaryWhat Is Network Redundancy?
Ring topology and RSTP that heal a broken link automatically so one cable fault never downs a site - explained.
Read → GlossaryWhat Is a Null Modem Cable?
The crossover serial cable that swaps TX and RX so two DTE devices can talk directly.
Read → GlossaryWhat Is an Omnidirectional Antenna?
The 360-degree master-station antenna that serves many remotes in a point-to-multipoint network.
Read → GlossaryWhat is a VLAN in an OT network?
Logical segmentation on shared switches to split PLC, HMI, camera, and vendor traffic, and its limits versus a firewall.
Read → GlossaryWhat is a plant information network?
The Purdue Level 3 tier that aggregates historian, MES, and reporting data above the control network.
Read → GlossaryWhat Is a Point-to-Multipoint Radio Network?
The star topology where one master radio polls many remotes over a single shared channel.
Read → GlossaryWhat is a power duty cycle in remote telemetry?
The fraction of time a load is on, which turns scary peak draw into the honest average that sizes a solar array.
Read → GlossaryWhat Is Power over Ethernet (PoE)?
Delivering DC power and data on one cable to field radios and cameras, with 802.3af, at, and bt classes.
Read → GlossaryPrivate APN or public cellular?
Public cellular suits a single outbound-only site; move to a private APN for controlled addressing, inbound reachability, and reduced exposure once you run a fleet.
Read → GlossaryWhat Are Cellular PSM and eDRX?
The cellular sleep modes that let a battery RTU stay dormant for hours, their power savings, and the reachability trade-off.
Read → GlossaryWhat is the Rapid Spanning Tree Protocol (RSTP)?
IEEE 802.1w loop prevention that blocks redundant links and reconverges in seconds using BPDUs and root bridges.
Read → GlossaryHow to Read HART Variables With a Modem
Wire across adequate loop resistance, read command 0 for identity, then command 3 for the values, and check the status.
Read → GlossaryHow do you recover a gateway stuck offline?
Check power and signal, climb a gentle-to-hard recovery ladder, verify the SIM and APN, and escalate with evidence if it fails.
Read → GlossaryHow do you reduce cellular data use on a gateway?
Split the bill to find the driver, slow polls and use report-by-exception, batch to trim overhead, and stop reconnect thrashing.
Read → GlossaryWhat Is a Redundant I/O Network and How Does It Keep Remote I/O Online?
Dual adapters, self-healing rings like DLR and MRP, and dual-media paths that survive a cut cable to remote I/O.
Read → GlossaryWhat is a redundant ring network?
A managed closed loop with a ring manager that survives a single break with fast self-healing recovery.
Read → GlossaryWhat is the requested packet interval (RPI)?
The millisecond interval that sets EtherNet/IP I/O update rate and, through a multiplier, the connection timeout.
Read → GlossaryWhat Is an RF Link Budget?
The gain-minus-loss math that predicts whether a SCADA radio link will actually close.
Read → GlossaryWhat Are RSRP and RSRQ in Cellular Link Quality?
The two LTE reference-signal metrics a technician reads when siting an antenna, and how they differ from RSSI.
Read → GlossaryWhat is a screened subnet in an OT network?
The back-to-back dual-firewall architecture wrapping a SCADA DMZ, and why two firewalls from different vendors beat one.
Read → GlossarySerial, cellular, or licensed radio backhaul?
A selection guide comparing reach, ownership, and recurring cost across wired and wireless links, with a rule for choosing.
Read → GlossaryWhat Is a Serial-to-Ethernet Converter?
The device server that puts legacy RS-232/RS-485 gear on an IP network - raw TCP vs virtual COM, explained.
Read → GlossaryHow do you set a gateway keepalive and deadman?
Pick a keepalive that beats the idle timeout without wasting data, and a deadman that tolerates one gap but flags a silent gateway.
Read → GlossarySet an MQTT Keepalive for a Cellular Link
Tune the keepalive shorter than carrier NAT timeout while meeting your offline-detection window without wasting data.
Read → GlossaryHow do you set a static IP with BOOTP or DHCP?
Capture the device by MAC, assign the address, then disable the client so it keeps the IP across reboots.
Read → GlossaryHow do you set the poll cycle for a radio SCADA network?
Budget per-remote time, set timeouts just past a normal reply, bound retries, and give critical points a faster sub-cycle within the freshness target.
Read → GlossaryHow do you set up a managed switch VLAN for OT?
Plan a VLAN per traffic class, assign device ports as access ports, trunk only the needed VLANs between switches, and verify isolation by test.
Read → GlossaryWhat Is SIM Connectivity Management?
The platform that provisions, monitors, and pools cellular SIMs across a large telemetry fleet - explained.
Read → GlossaryWhat is a SPAN port vs a network TAP for OT monitoring?
How an IDS sensor gets a traffic copy: a switch mirror port versus an inline TAP, and why TAPs avoid silent drops.
Read → GlossaryWhat Is a LoRaWAN Spreading Factor?
The SF7-SF12 dial that trades range against airtime and battery, how ADR tunes it, and why high SF congests gateways.
Read → GlossaryWhat Is a Subnet Mask and CIDR for SCADA?
The practical minimum of subnet masks and /24 CIDR an automation tech needs to lay out a control network where every device reaches the SCADA host.
Read → GlossaryHow do you survey cellular signal at a site?
Sweep the site, read RSRP and RSRQ per band and carrier, log the numbers with height, and pick the steadiest spot.
Read → GlossaryHow do you swap a failed cellular gateway?
Confirm the gateway is the fault, move the SIM and saved config to the replacement, verify it reaches your host, and update records.
Read → GlossaryHow do you test a cellular link before leaving?
Confirm real data reaches your host, power-cycle and confirm recovery, check the signal margin, and record the sign-off.
Read → GlossaryWhat is the difference between a VLAN trunk port and an access port?
Access ports carry one untagged VLAN to a device; trunks carry many tagged VLANs between switches, plus the native-VLAN gotcha.
Read → GlossaryHow do you verify a radio path with Fresnel math?
Work the Fresnel-zone radius and earth-curvature bulge symbolically, then confirm 60 percent clearance at every obstruction before you climb.
Read → GlossaryHow do you check data usage against polling math?
Estimate bytes from poll rate and payload plus overhead and reconnects, compare to the carrier meter, and explain the gap.
Read → GlossaryWhat Is a Virtual IP Address in a Failover Setup?
The floating address that always points to the current primary node, making failover seamless to field devices.
Read → GlossaryWhat Is a WirelessHART Gateway Uplink?
The wired interface that republishes the whole mesh over HART-IP, Modbus, or OPC UA so one host reads every device.
Read → GlossaryHow WirelessHART Mesh Routing Works
Graph routing gives each device several next hops for resilience while source routing pins one path for diagnostics.
Read → GlossaryWhat Is the WirelessHART Network Manager?
The centralized brain in the gateway that schedules slots, defines routes, and heals the mesh, making it deterministic.
Read → GlossaryWhat Is a Yagi Antenna?
The directional gain antenna aimed from a remote RTU site back to a distant master station.
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