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Belt1_Current crossed 30 A at 11:42:13.412 UTC. The OPC UA server stamped that value 11:42:13.592, the gateway published it at 11:42:13.637, and the row reached the table at 11:42:14.297. One event, four times, 885 ms apart on a day when nothing at all was wrong. Store the second one. The OPC UA SourceTimestamp is the … Read more
1200 tags collected once a second is 160,704,000 values a day, and at the 12 bytes a historian typically spends on a timestamp, a value and a status that is 1.93 GB a day and 704 GB a year. The same 1200 tags, with a deadband at the collector and a compression test at the … Read more
One firewall rule is usually all a plant data project asks for: TCP 1433 outbound, from a gateway at 192.168.1.40 on the cell network to a SQL Server at 10.20.4.16 on the business network. That rule gets refused, and the refusal is right. What gets approved instead is a broker sitting in a demilitarised zone … Read more
An Edge Gateway That Buffers: Six Hours Offline, and Then What Six hours of the carton transfer at its real change rates is 2.12 MB. Four machines on the same gateway is 8.49 MB. The same four machines with every tag published every second and no deadband on anything is 31.66 MB, and that is … Read more
Sparkplug B Properly: Birth and Death Certificates, Metrics and Rebirth The first message the carton transfer gateway sends is 592 bytes on the topic spBv1.0/Plant2_CartonLine/NBIRTH/GW-TR14, it carries all 19 metrics the node will ever publish, and it goes out at QoS 0 with the retain flag clear. Everything about that sentence looks wrong to somebody … Read more
An MQTT Broker for Plant Data: Topics, QoS, Retained Messages and Last Will The topic string plant2/pack/carton1/tr14/belt1/amps is 42 bytes. The float it carries is four. Every publish of the motor current on one belt of the carton transfer therefore spends ten times as much on saying where the number came from as on the … Read more
Arrays, UDTs and Structures Over OPC UA: What the Client Actually Sees Insert one DINT called Jam_Count into the TR14_Belt user-defined type, put it after the State member where it belongs logically, and download to the 1756-L83E. Fault_Code moves from byte 4 to byte 8, and Starts, Run_Seconds, Speed_mps, Motor_Amps and Last_Fault_S each move four … Read more
Browsing an OPC UA Server Against a Static Tag List: Which One, and When Each Is Wrong Node i=2255 is the NamespaceArray, and one Read of it is the single most-skipped call in industrial OPC UA. Skip it and you type ns=3 into a client, which works for a year and then reads the wrong … Read more
OPC UA Security Policies and User Authentication: What to Enable, and What It Costs One RSA-2048 private-key operation measured 3.363 ms on the laptop this was written on, and one pass of AES-256 over a kilobyte of notification measured about 2.1 microseconds. That ratio, roughly sixteen hundred to one, is the whole of the OPC … Read more
OPC UA Certificates: Trust, Rejection, and Why the First Handshake Fails BadSecurityChecksFailed, status 0x80130000, is the answer an OPC UA server gives when it has decided not to talk to you and is not permitted to say why. Part 6 of the specification is explicit about it: the Reason string in an abort message “shall … Read more
OPC DA to OPC UA: What Changed, and the Tunneller You No Longer Need KB5004442 stopped being optional on 14 March 2023, and with it went the last registry value that could keep an OPC DA link alive between two Windows machines. RequireIntegrityActivationAuthenticationLevel is still sitting under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Ole\AppCompat on every machine somebody set it on, … Read more
Seal_Temp has read 182.4 °C since about 04:00, the quality field next to it says Good, and the trend behind it is a flat line eleven hours long. The bagger has run four product changes in that time and the seal jaws are visibly hot. Nothing on the SCADA is in alarm, nothing in the … Read more