CX4阻挡探测校准

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CX4 Obstruction Detection Calibration

Last Edited 05/01/2001 08:09:31 PM

Product: Synchron CX

Chapter: CX PRO

Section: Obstruction Detection

Summary

The calibration procedure for CX4 obstruction detection and correction (ODC) is described below.

Background

The obstruction Detection and Correction (ODC) feature for CX PRO includes an automatic onboard calibration process. The calibration values are stored in nonvolatile memory and are checked against predetermined limits.

Procedure

The CX4 obstruction detection calibration procedure should be performed after installing new obstruction detection hardware. In addition, when ODC hardware is installed or new tubing is installed, a minimum of 10 internal probe rinses should be performed on the sample probe before running the calibration procedure. The primes ensure the lines are degassed sufficiently to provide a good calibration. Access the calibration screen as follows: From the Main Screen, select F4 Special Functions. From the next screen, select option 6. Maintenance. From the next screen, select option 5. CX4 Obstruction Detection Calibration.

	Step	Action
		The calibration procedure takes 4 measurements. Each are described below.
	1	Probe measurement (no liquid) - Value 1 on the screen This value represents the vacuum generated by the column of fluid in the sample probe. Gravity is the only force acting on the column of fluid and the gravitational pull causes a slight vacuum to be felt by the diaphragm in the obstruction assembly. Home the CX system - Top 2 LEDs on motor driver 3 are ON. Perform one internal probe prime Send a command to PIC to go into calibration mode - First and third LEDs on motor driver 3 are ON. Send a command to PIC to take the first measurement Read PIC status byte and data byte
	2	DI water measurement - Value 2 on the screen Move the sample wheel to slot 1 cup 1 position Aspirate an air slug Move the sample probe and level sense DI water Send a command to PIC to take the second measurement Aspirate 25 uL water Read PIC status byte and data byte
	3	Sample Obstruction measurement - Value 3 on the screen This value is calculated from the DI water measurement. It is ~15% of the DI water measurement value (value 2) This value represents a ~0.5 uL clot.
	4	Blowout measurement - Value 4 on the screen When fluid is pushed through the probe, the diaphragm is subjected to the pressure required to push fluid out of the probe. This value will be used to determine if the probe is obstructed. Go to wash station and inject what was aspirated in previous steps. Aspirate DI water Send a command to PIC to take the fourth measurement Dispense the DI water Read PIC status byte and data byte
	5	Obstruction Detection Calibration Status Displayed on Screen Display calibration values on the screen. If all Pass, ask operator if want to save values (Done with Obstruction detection calibration below). If Fail, notify operator of failure and provide option to exit calibration procedure (Abort Sequence below).
	6	Done with Obstruction detection calibration Send a command to PIC to write the calibration values to EEPROM If PIC encounters an error in writing EEPROM, a pop-up message appears. Read PIC status byte to confirm calibration was saved PIC automatically performs a local software reset - Top 2 LEDs on motor driver 3 are ON.
	7	Abort Sequence If operator aborts calibration, CA Abort command is sent to PIC PIC will perform local software reset and reload previous calibration values. Home the CX system

Status Byte

The status byte of the PIC is read several times during the calibration. Meaning of the status byte for calibration are below, however, these values are not viewable (event with cxlogger). 04 hex = No errors, calibration data is good 14 hex = No errors, calibration data is bad x8 hex = Error occurred, stop calibration. High nibble (x) gives specific error code.

Typical Values/Limits

The limits for each measurement are provided below. The middle value represents typical values for in-house instruments. All values are in hexadecimal (hex). Probe Measurement (value 1): 6A<76<82 hex DI Water Measurement (value 2): 59<65<71 hex Sample Obstruction Measurement (value 3): 4A<56<62 hex Blowout Measurement (value 4): 8C<98<A4 hex

Troubleshooting

The following troubleshooting tips should be useful if ODC calibration fails.

	Symptom	Troubleshooting Tips
	Values 1, 2 and 3 all FAIL and value 4 PASSes.	Check cable connection to motor driver 3 board.
	Values 2 and 3 FAIL and values 1 and 4 PASS	Value 2 is determined while aspirating sample. If it fails, value 3 will fail. This failure mode is most likely associated with the fluid level in the cup. Check the following: Does the cup contain fluid? Either cup was empty or insufficient fluid was in cup for procedure. Put appropriate fluid in cup and repeat procedure. Does position 1 of the sector contain a cup? This procedure does not flag level sense errors (insufficient fluid or no fluid). Put container with appropriate fluid in position 1 of sector and repeat procedure.
	Value 1 PASSes and Values 2, 3 and 4 all FAIL	Value 2 is determined while aspirating sample. If it fails, value 3 will fail. Value 4 is determined while pushing the fluid out of the probe. The limits are set with the assumption the calibration is being performed with an aqueous solution. This failure mode is most likely associated with the fluid in the cup. Check the following: Is the fluid in the cup aqueous (DI water, saline, aqueous calibrator, etc)? If not, put appropriate fluid in cup and repeat procedure.
	Vales 1, 2, 3 and 4 all FAIL	The most likely scenario for all values failing is a clogged probe or a ruptured membrane on the transducer. The main difference between a clogged probe and a blown sensor is the magnitude of values 1and 2. If the sensor is ruptured, all the values will be low. For one in-house system which had a ruptured CX4 ODC assembly, value 1 was 00, value 2 was 01, value 3 was F1 and value 4 was 12. For one in-house system which had a clogged CX4 sample probe, value 1 was E0, value 2 was 07, value 3 was F8 and value 4 was 12.