FPS Series — PLC Fatal Error: Re-initialization and Parameter Restore – South-Tek Systems

Applies to: South-Tek fire protection nitrogen generators with the touchscreen controller — FPS-1650, FPS-3250, FPS-5000, FPS-10000, FPS-16500 and FPS-22500. Legacy fire protection models with the same touchscreen are covered once Tech Support confirms the controller for that serial number.
The FPS-500, FPS-900 and FPS-900-RS use a different controller: a small display driven by Next, Set and up-down buttons. None of the screens below exist on it. Do not attempt any step on that controller — open a support ticket instead.
This article gives the fire protection values. The same touchscreen controller is used on other South-Tek lines — the N2-GEN TS, CS and S series, the 02CPi and 04CPi, and HPCF units — and the re-initialization steps are the same on all of them, but several factory settings differ by line. If this unit is not a fire protection model, do not use the values in this article. Open a support ticket and Tech Support will give you the values for that line.
Work through this procedure only with a South-Tek Tech Support ticket open for this unit. The Factory Settings menu is locked at the factory, the codes and the spec sheet are issued only through that ticket, and changing the controller's setup without South-Tek's written consent voids the fire protection system's performance specifications.

Symptom

The PLC displays a fatal error screen and will not boot normally. Cycling power appears to recover the unit, but the controller runs only a few minutes before the fatal error returns.

A fatal error indicates the controller's stored program or memory has been corrupted. Re-initializing the PLC and reloading the unit's parameters resolves most occurrences.

Before you begin

⚠ Warning — this procedure is a fire protection impairment It takes the generator out of service for 30 to 45 minutes at the controller, and the unit cannot be released until it has run monitored for a further 15 to 30 minutes. Declare the impairment for the whole of that window. Nothing supervises the riser while the controller is down — any automatic air bypass is operated by the same controller. Before you start: notify the building owner or their impairment coordinator and the alarm monitoring company, have the fire alarm points that monitor this generator put on test, and tag the system under the site's impairment program. Record the riser's supervisory pressure and whatever the fire alarm panel is already showing — read the pressure at the riser's own gauge or at the panel, not from the generator's tank pressure. Do not begin until the building owner or their impairment coordinator has authorized the outage. Before you leave, confirm: the unit back in Running or Standby on nitrogen and not in bypass, the riser back at the pressure you recorded, the panel showing only the conditions you recorded on arrival, the points off test and the tag cleared.

⚠ Warning This procedure is done entirely at the touchscreen on the front of the cabinet, with the unit powered and the cabinet closed. Do not open the enclosure, do not lock out the controller's power, and do not relieve stored pressure — no step below needs any of it, the controller has to stay powered, and venting the nitrogen tank takes make-up gas away from the riser. If the fault turns out to need work inside the cabinet, stop: that is separate work, with its own lockout/tagout and its own impairment scope. The cabinet holds stored pressure and live electrical circuits, and only qualified personnel should open it.

⚠ Warning — Do not begin without the factory settings spec sheet Re-initializing erases the controller's stored setup, and the unit cannot be returned to service without the values recorded on the factory settings spec sheet for that serial number. Sheets are not interchangeable between units. Request it from South-Tek Tech Support — open a ticket with the model and serial number in the subject line — and have it open in front of you at the controller, printed or on a device, before you touch the screen. Confirm it carries all four things this procedure needs: the info-mode password (Step A), the unlock calculation (Step B), the factory access code (Step C) and the sensor calibration values (Step D). All four come with the sheet, not separately. If any one of them is missing, do not start — Step A erases the controller and there is no way back without all four.

Have the following ready before you begin:

The model number and serial number from the unit's nameplate.
The factory settings spec sheet for that serial number, confirmed to carry all four items listed in the warning above.

Step A — Re-initialize the PLC

Press and hold a blank area of the touchscreen — not one of the on-screen buttons — for about 5 seconds.
When INFO MODE appears, tap Enter INFO Mode.
Enter the info-mode password from the factory settings spec sheet and press Enter (the large left-arrow key at the far right of the keypad).
Tap Working Mode.
Tap Init in the bottom right corner. Init erases the controller's stored setup and cannot be undone — do not tap it unless the spec sheet is open in front of you and the impairment has been declared, notified and tagged. The PLC re-initializes and restarts.

Step B — Enter the unlock code

After the restart the PLC asks for a code.

Tap Get ID # and note the number the controller displays.
Apply the unlock calculation from the factory settings spec sheet to that number to produce the code. Enter the result and press Enter.

ℹ Note The controller generates a new ID number every time it is initialized, so a code calculated earlier will not work. If the code is rejected, tap Get ID # again and recalculate from the number it shows. Do not run Init a second time.

Step C — Load factory defaults for the model

Open Factory Settings, enter the factory access code issued with the spec sheet, then tap Factory Settings again.
Tap Set Factory Defaults, then select the model shown on the unit's nameplate.
Turn on Equip. Status. It should turn green and read On.
Still in Factory Settings, tap the clock icon to the left of Set Factory Defaults.
In the O2 Sensor field, enter 0 to select the O2% option. Fire protection units use the percent-range sensor, so 0 is correct whether or not a sensor is fitted to this unit.

▲ Attention Selecting the wrong model at Set Factory Defaults loads the wrong operating parameters. Confirm the model against the nameplate — not the sales order, not the ticket, not the spec sheet. If the nameplate and the spec sheet name different models, stop and call Tech Support. If defaults for the wrong model have already been loaded, re-select the correct model and re-enter every value in Step D.

Step D — Enter sensor calibration values

Back out of Factory Settings to the main menu, tap Sys Settings, then tap Sensor Calibration.
Enter the values from the factory settings spec sheet in the N2 Tank Pressure Calibration screen and, on units with an oxygen sensor fitted, the O2 % Concentration Calibration screen. If the Sensor Calibration screen lists any other sensor for this unit, those calibrations were erased too — enter their values from the sheet as well.

Calibration screen	Fields	Source of values
N2 Tank Pressure Calibration	Low Raw, Low Value, High Raw, High Value. Current Raw and Current Reading are displayed, not entered.	Factory settings spec sheet for this serial number
O2 % Concentration Calibration	Low Raw, Low Value, High Raw, High Value. Current Raw and Current Reading are displayed, not entered.	Factory settings spec sheet. If the sheet marks this screen N/A, no oxygen sensor is fitted and the screen does not appear.

Sensor calibration entry screen showing the Low Raw, Low Value, High Raw and High Value fields — Calibration value entry screen

⚠ Warning Never enter calibration values taken from a different unit, a manual, or a previous ticket. Enter only what appears on the factory settings spec sheet for this serial number. Raw counts are specific to the transducer and sensor installed in that generator. If the transducer or the oxygen sensor has been replaced since the unit shipped, the counts on the sheet belong to the old part — stop and call Tech Support. Do the same if a value is missing or illegible: do not interpolate and do not estimate. Wrong values produce believable but incorrect pressure and purity readings, which on a fire-protection system can mask a genuine low-purity or low-pressure condition.

Return to service

Before releasing the unit, confirm all of the following.

The fatal error does not return over 15 to 30 minutes powered, including at least one complete run-to-standby cycle. The unit will not run continuously — it stops producing once the tank reaches cut-out pressure. If the tank is already at cut-out and the unit stays in Standby for the whole window, that is normal and this check still counts — note on the ticket that the run-cycle and purity checks could not be performed.
The model shown on screen matches the nameplate.
With the unit in standby, the N2 tank pressure on the touchscreen agrees with the unit's nitrogen storage pressure gauge on the outside of the cabinet — not a riser or air-maintenance-device gauge, which read downstream of a regulator. Read both at the same moment, without opening the enclosure. This catches a gross calibration error only. If the two disagree, do not release the unit — re-check every Low Raw, Low Value, High Raw and High Value entry against the sheet and call Tech Support.
Where an oxygen sensor is fitted: after a full run cycle, the purity reading is at or above this site's low-purity alarm point and steady or still rising. A reading taken straight after re-initialization is still recovering and proves nothing.
In Sys Settings and Alarm Settings, the cut-in and cut-out setpoints, the N2 tank pressure alarm point and cut-out, the BlastOff timer, and — where an oxygen sensor is fitted — the purity alarm point and cut-out all read what the spec sheet shows.
Then close out the impairment: the unit back in Running or Standby on nitrogen and not in bypass, the riser back at the pressure you recorded, the panel showing only the conditions you recorded on arrival. If any one of those is not true, leave the impairment open and fix the cause before you release the system. Notify the building owner or their impairment coordinator and the alarm monitoring company that the generator is back in service, take the points off test and clear the tag.

If the fatal error returns

A fatal error that reappears after a successful re-initialization and parameter restore generally indicates the PLC itself has failed rather than a corrupted program. In that case the controller should be replaced. Open a support ticket with the model number, serial number, a photo of the fault screen, and a short description of what the unit did after the re-initialization, and Tech Support will quote the replacement PLC. Until it is replaced this generator is not supervising the riser, so the impairment stays open: leave the tag in place, keep the points on test and the alarm monitoring company informed, and tell the building owner or their impairment coordinator that the system stays impaired until the replacement controller is fitted, its Step D values entered, and every check under Return to service above passes.

Note — Replacement PLCs: A replacement controller ships preloaded for the model but still requires the unit-specific values from Step D. Request the factory settings spec sheet at the same time you order the PLC so the swap can be completed in one visit.

Need help? South-Tek Systems Service — Phone: (910) 415-1880 · Open a support ticket at support@southteksystems911.zendesk.com or through the Help Center.