Logix Designer, RSLogix 500/5000, RSLinx, FactoryTalk and the faults you meet on a ControlLogix or CompactLogix line.
CTU, CTD and RES: The Count That Keeps Going Past the Preset buffer_count.ACC reads 41,206 against a preset of 500, and .DN has been true since some time on Tuesday. The line is running normally, the zone-full interlock has not released since then, and nobody can find the fault because there is not one. A … Read more
BTD: Pulling a Field of Bits Out of One Word and Into Another The status DINT coming back from the bench scale reads 306,997. The weight is 1,199, and the rest of that number is a units code, a stable flag and a sequence counter, packed into the same word because the vendor had thirty-two … Read more
MOV, MVM and CLR: Moving a Word, and Moving Only Some of Its Bits MOV a DINT holding 123456 into an INT tag and the INT reads -7616. No fault light, no message, the rung stays exactly as green as it was, and the only record that anything was lost is S:V, which nobody has … Read more
When an Axis Will Not Enable: the Six Gates MSO Has to Pass Before Anything Moves The MSO rung goes true on a 2198-D032-ERS3 axis, MSO_1.EN sets, and then nothing happens: no .DN, no .ER, no error code to look up, and the machine sits there. Axis_01.AxisState reads 5. Five is Inhibited, and a start … Read more
The Feedback Fault That Is Not the Encoder: FLT S45, the DSL Cable and the Ground That Hides It A 2198-D020-ERS3 running a VPL-B1306F has thrown FLT S45 – FDBK COMM FL four times in six weeks, and there is a third motor on order. The drive has been measuring the actual cause the entire … Read more
Position Error and Following Error on a Kinetix Axis: What a Trend Says That FLT S54 Does Not A 2198-D020-ERS3 threw FLT S54 – POSN ERROR at 14:02 and again at 14:19, and the fault-code spreadsheet describes it in one sentence: the position error of the position control loop exceeded Position Error Tolerance for longer … Read more
Axis Faults on a Logix Motion Axis: What AxisFault, MotionFault and the Attributes Are Telling You On a 1756-L83E, Axis_01.AxisFault reads 1, Axis_01.MotionFault reads 0, and the 2198-D032-ERS3 in the panel is showing FLT S54 – POSN ERROR. Somebody will now spend twenty minutes looking for a motion fault that does not exist, because the … Read more
Reading a Kinetix 5700 Fault at the Drive: the Display, the Fault Log and the Four Places to Look The LCD on a 2198-D032-ERS3 reads FLT S45 – FDBK COMM FL, the MOD indicator above it is flashing red, and the line has been down for eleven minutes. Before anyone fetches a laptop, the drive … Read more
Registration and the MAR Instruction: Catching a Mark at Speed on a Kinetix 5700 A Kinetix 5700 inverter latches a registration event with ±3 µs accuracy and 700 ns repeatability, and its propagation delay is compensated to zero. At 1.5 m/s that accuracy figure is 4.5 µm of position uncertainty. The photoeye in front of … Read more
Soft Travel Limits, Hard Limits and the Overtravel That Faults a Kinetix Axis A registration input on a Kinetix 5700 inverter gets a 12.0 µs pulse reject filter. The overtravel input, on the same IOD connector and the same silicon, gets the 20 ms nominal debounce that every other input function gets. At 500 mm/s … Read more
Scaling a Kinetix Axis in Real Units: Position Units, the Conversion Constant and the Gearbox A new Kinetix axis is scaled one Position Unit per motor rev, at 1,000,000 Motion Counts per rev, and on Unlimited travel that axis rolls its position accumulator over after 2,147 revolutions. The motion runs through the rollover perfectly smoothly. … Read more
Tuning a Kinetix 5700 Axis: Load Ratio, Bandwidth and the Autotune That Lies Loop Response on the General page of a Kinetix axis is a three-item dropdown, and on a drive with the default 1.5 ms model time constant it moves the position loop between 8.2 Hz and 101.7 Hz. That is a factor of … Read more