Healthy Lifestyle & Kidney Health

The LLC / LLS Architecture

Dual-Processor

LLC (Controller): Executes the physical action (e.g., turns on a pump, closes a valve, applies voltage).
LLS (Supervisor): Acts as the independent watchdog. It uses separate sensors to verify the LLC's action actually happened.
The Handshake: If the LLC performs step 1 and the LLS detects the correct physical response, the LLS sends a confirmation signal (switching 24V for 3 seconds). This handshake tells the LLC to move to step 2. If the LLS does not see the expected result, the test halts, and the machine throws an LLC/LLS status code.

[LLC] Executes Step 1 ──> [LLS] Verifies Physical Response
│
▼
[Confirmation Signal] 24V for 3 seconds ──> [LLC] Proceeds to Step 2
│
❌ If LLS does NOT see expected result → TEST HALTS

Key Concept:

The LLS does not execute commands. Its only job is to verify that the LLC's commands produced the expected result. If the LLS disagrees, the machine halts immediately.

Critical LLC/LLS Codes and Troubleshooting

Error Codes

When an error occurs, the code usually points to a specific phase of a subsystem test.

System	LLC / LLS Code	Typical Cause of Failure	Primary Troubleshooting Action
Blood Leak	1102x / 1110x	Air bubbles, dirty optics, fluid leak	Purge air, clean sensor glass, run TSM 1.1x
UF / Pressure	1230x / LLS 12021	UF pump defect, reed sensor fail	Check for kinked drain hose, run TSM 1.17
UF Valves	1235x / 1240x	Leaking VDE, VBP, or VDABK valves	Replace valve membranes, check O-rings
Heater	2510x / 2610x	Heavy calcification, triac failure	Perform decalcification, check SMPS-MC board
HDF Online	LLS 15120	HFB filter blocked	Replace filter, run TSM 1.19 leak test
Sub Leakage	LLS 40000 series	Disposables leaking, pump deviation	Check check-valves (DDE/RVDA), align pumps

Critical:

Never replace a board or pump before ruling out passive causes. The LLS is highly sensitive to air bubbles and kinked lines.

Subsystem Troubleshooting Details

Deep Dive

1. Ultrafiltration (UF) and Pressure Tests

12xxx Series

These tests ensure the machine can accurately pull and hold negative pressure to safely remove fluid from the patient.

Phase 3 (1230x): The LLC attempts to reduce pressure using the UF pump. If the pressure drops too slowly (or not at all), the LLS halts the test.

Troubleshooting: Exclude "passive" causes first — ensure the drain hose is not kinked or blocked. If the path is clear, suspect a defective UF pump or a misaligned reed sensor.

Phase 4/5 (1235x - 1240x): The LLC tests the integrity of the pressure-holding valves (VBP, VDE, VDABK).

Troubleshooting: If pressure increases when it should be static, the VDE or VBP valve is leaking. If pressure drops, the VDABK valves or the UF pump itself is leaking backward. Rebuild the suspect valves.

2. Blood Leak Detector (BLD)

11xxx Series

The BLD uses red and green LEDs to monitor the dialysate effluent for hemoglobin.

Failure Condition: The LLC turns on the LEDs, and the LLS expects a specific voltage differential between the red and green receivers.

Troubleshooting: 90% of BLD self-test failures are caused by air in the system or a dirty glass tube. Purge the machine thoroughly. If it still fails, physically clean the BLD tube. If the electronics have drifted, a recalibration via the TSM Service Program is required.

3. Flow and Balance Chamber Failures

Balance & Inlet

While not always giving a strict 5-digit LLS code on the front screen, balance chamber and water inlet issues are the most common mechanical failures.

Water Supply Disturbed: Triggered if inlet pressure is too low or the DMV (pressure reducer) is out of offset.

Troubleshooting: Enter TSM low-level test 1.9 (Water Inlet). Install a pressure gauge, open the inlet valve (VVBE), and set the FPE pump to 1200 ml/min. Adjust the DMV to specification.

DFS Test Failed: Indicates an imbalance in the flow system.

Troubleshooting: Check for a torn balance chamber membrane, worn out FPE/FPA pumps, or a blocked flow path. Always replace balance chamber membranes in pairs.

General Maintenance Rules for Dialog+

Prevention

To prevent the majority of LLC/LLS handshake failures:

1. Exclude the Passive Elements
Never replace a board or pump before verifying that tubes aren't kinked, O-rings aren't cracked, and the system is completely free of air. The LLS is highly sensitive to air bubbles disrupting pressure and optical tests.
2. Diligent Decalcification
Heater and flow valve failures are heavily tied to calcium build-up. Ensure the clinic's decalcification program with Citric Acid 50% is strictly followed.
3. TSM is Your Diagnostic Tool
The Technical Service Mode (TSM) allows you to isolate and run individual low-level tests (e.g., TSM 1.2 for the arterial pump, TSM 1.15 for the balance chamber) rather than waiting for the sequential self-test to fail.

                
                Preventative Maintenance Summary:
                Daily: Visual inspection of lines and couplings.
Weekly: Conductivity and temperature calibration check.
Monthly: Hot Citric Acid decalcification cycle.
Quarterly: Full TSM diagnostic suite and sensor recalibration.

            

Pro Tip:

Most fluid-side errors are preventable. Regular decalcification cycles cost minutes — replacing hydraulic components costs thousands.

Dialog+ · Medical Reference

LLC / LLS Architecture — The Handshake