[Verse 1]
Down in the plant where the steam pipes hum,
a little gray box counts the turns of a drum,
that's the PLC, bolted to a valve and a gauge,
reading the world every scan of its cage.
Miles down the pipeline, past the last fence door,
sits an RTU on a concrete floor,
whispering numbers on a radio thread,
telling the control room the tank isn't dead.
[Chorus]
P-L-C, R-T-U, H-M-I on the screen,
SCADA's the eye, DCS keeps it clean,
historian's the diary, writes down every beat,
safety system's the hand that pulls back the heat,
say it slow now, layer by layer,
that's how the physical world stays square.
[Verse 2]
The HMI's a window, colored and bright,
green means it's humming, red means it bit,
SCADA's the spider spread over the field,
DCS is the brain where the batches get sealed,
historian's the librarian, never forgets a trend,
and the safety system's the one that won't bend,
it trips the breaker before the boiler screams,
independent of logic, guarding the seams.
[Chorus]
P-L-C, R-T-U, H-M-I on the screen,
SCADA's the eye, DCS keeps it clean,
historian's the diary, writes down every beat,
safety system's the hand that pulls back the heat.
[Verse 3]
Picture a pyramid, Purdue drew the plan,
level zero's the metal, the valve and the fan,
climb to the plant floor, controllers in a row,
level three's the office that watches the flow.
But somebody ran a cable, thought it'd save some time,
straight from the payroll server to the turbine line,
that's the original sin, a wall with a hole,
and ransomware wandered in and swallowed control.
[Verse 4]
Modbus TCP talks plain, no lock on its gate,
DNP3 logs events out at the substation freight,
IEC sixty-one-eight-fifty runs the breakers on the grid,
OPC UA wraps the message, encrypted amid.
Open up Wireshark, watch the function codes fly,
read a coil, write a register, catch it with your eye.
[Bridge]
In the lab tonight, OpenPLC wakes up slow,
ScadaBR paints a pump station aglow,
tank's filling steady, the float arm climbs high,
then Python reaches in — one packet slips by,
forces the coil open, the pump won't ever stop,
that's the lesson learned when you watch a system drop.
[Chorus]
P-L-C, R-T-U, H-M-I on the screen,
SCADA's the eye, DCS keeps it clean,
historian's the diary, writes down every beat,
safety system's the hand that pulls back the heat,
say it slow now, layer by layer,
that's how the physical world stays square.
[Outro]
Crack the spine on Knapp, industrial and true,
eight-hundred-eighty-two, revision three for you,
PLC, RTU, HMI, SCADA, DCS, historian, safety line —
that's the physical world, now keep it in line.