Atlas Scientific EZO-pH Manual
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Atlas Scientific EZO-pH Manual

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pH Probe
Silver / silver chloride
Reads
Range
Resolution
Response time
Max pressure
Max depth
Temperature range °C
Cable length
Internal temperature sensor
Time before recalibration
Life expectancy
Maintenance
pH
0 − 14
+/- 0.0001
95% in 1s
100 PSI
60m (197 ft)
1 − 99 °C
1 meter
No
~1 Year
~2.5 Years +
N/A
V 3.1
Revised 12/12/18

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  • Page 1 V 3.1 Revised 12/12/18 pH Probe Silver / silver chloride Reads 0 − 14 Range +/- 0.0001 Resolution 95% in 1s Response time Max pressure 100 PSI Max depth 60m (197 ft) 1 − 99 °C Temperature range °C 1 meter Cable length Internal temperature sensor ~1 Year...
  • Page 2 • Beer, wine and other liquor (4.7”) This pH probe can be fully submerged in fresh or salt water, up to the BNC connector indefinitely. Sensing area 15.55mm (0.61”) 12mm (0.47”) Ø 14.3mm Ø 2.85mm Soaker bottle ~3.8 pH Copyright © Atlas Scientific LLC...
  • Page 3 Acid: pH < 7 Neutral: pH = 7 Base: pH > 7 Silver wire Junction Silver chloride KCL reference solution Reference wire Copyright © Atlas Scientific LLC...
  • Page 4 Because a pH probe is a passive device it can pick up voltages that are transmitted through the solution being measured. This will result in incorrect readings and will slowly damage the pH probe over time. In this instance, proper isolation is required. Copyright © Atlas Scientific LLC...
  • Page 5 NEVER EXTEND THE CABLE WITH CHEAP JUMPER WIRES! DO NOT CUT THE PROBE CABLE WITHOUT REFERING TO THIS DOCUMENT! Copyright © Atlas Scientific LLC...
  • Page 6 DO NOT MAKE YOUR OWN UNSHIELDED CABLES! ONLY USE SHIELDED CABLES. REFER TO THIS DOCUMENT! Copyright © Atlas Scientific LLC...
  • Page 7 Extending the probe cable length You can extend the cable to greater than 100 meters with no loss of signal. Atlas Scientific has tested up to 300 meters without a problem, however you run the risk of turning your pH probe into an antennae, picking up noise along the length of your cable.
  • Page 8 During shipment the air bubble in the probes stem may move into the bulb area. If bubbles are seen in the bulb area, hold the probe by its top cap and shake downward as done with a clinical thermometer. Bubbles Copyright © Atlas Scientific LLC...
  • Page 9 A light bleach solution or even a 5 – 10% hydrochloric acid (HCl) soak for a few minutes, often removes many coatings. If cleaning does not restore performance, reconditioning may be tried. Do not use a brush or abrasive materials on the pH probe. Copyright © Atlas Scientific LLC...
  • Page 10 Probe reconditioning When reconditioning your pH probe is required due to aging, we recommend you use the Atlas Scientific pH probe reconditioning kit. Copyright © Atlas Scientific LLC...
  • Page 11 V 5.1 Revised 10/23/18 EZO-pH ™ Embedded pH Circuit Reads .001 − 14.000 Range .001 Resolution +/– 0.002 Accuracy 1 reading per sec Response time Any type & brand Supported probes 1, 2, 3 point Calibration Temp compensation UART & I...
  • Page 12 This device has been designed to be soldered and can be soldered at any time. Once that decision has been made, Atlas Scientific no longer assumes responsibility for the device’s continued operation.

  • Page 13: Table Of Contents

    Sleep mode/low power Factory reset Change baud rate Change to UART mode Protocol lock Manual switching to UART Factory reset Change to I C mode Manual switching to I Circuit footprint Datasheet change log Warranty Copyright © Atlas Scientific LLC...

  • Page 14: Circuit Dimensions

    -65 °C 125 °C (EZO™ pH) 13.8 mA 13.8 mA Operational temperature -40 °C 25 °C 85 °C (EZO™ pH) 14.5 mA 13.9 mA 0.995 mA 3.3V 13.3 mA 13.3 mA 3.3V 5.5V Copyright © Atlas Scientific LLC r 0.1...

  • Page 15: Circuit Identification

    Legacy pH circuit ™ Viewing correct datasheet Viewing incorrect datasheet Click here to view legacy datasheet Copyright © Atlas Scientific LLC r 0.1...

  • Page 16: Operating Principle

    (outside the probe vs. inside the probe) creates a VERY small current. This current is proportional to the concentration of hydrogen ions in the liquid being measured. Acid: pH < 7 Neutral: pH = 7 Base: pH > 7 Silver wire Junction Silver chloride KCL reference solution Reference wire Copyright © Atlas Scientific LLC...

  • Page 17: Calibration Theory

    4. Calibrate the midpoint value using the command "Cal,mid,n". “Cal,low,n” Where "n" is any floating point value that represents the calibration midpoint. 5. Do not pour the calibration solution back into the bottle. 1:00 − 2:00 Copyright © Atlas Scientific LLC...
  • Page 18 5. Do not pour the calibration solution back into the bottle. Issuing the cal,mid command after the EZO pH circuit ™ has been calibrated will clear the other calibration points. Full calibration will have to be redone. Copyright © Atlas Scientific LLC...

  • Page 19: Power And Data Isolation

    ™ the EZO Conductivity or Dissolved Oxygen circuit. ™ Correct Incorrect Correct Incorrect Basic EZO Inline Voltage Isolator Without isolation, Conductivity and Dissolved Oxygen readings will effect pH accuracy. Copyright © Atlas Scientific LLC r 0.1...
  • Page 20 SCL2 SCL1 RX/SCL TX/SDA SDA2 SDA1 RX/SCL TX/SDA GNDP 0.1uf GNDP GNDISO 1.5K GNDP GNDISO 4.7K GNDP GNDISO 4.7K ISO-GND 10uF PDIS GNDISO 0.1uF ISO-VCC 0.1uF N-FET ISO-VCC 10uF Non-isolated Isolated 10uF ISO-GND Copyright © Atlas Scientific LLC r 0.2...

  • Page 21: Correct Wiring

    Part # Part # ISCCB USB-ISO Incorrect wiring Extended leads Sloppy setup Perfboards or Protoboards *Embedded into your device NEVER use Perfboards *Only after you are familar or Protoboards with EZO circuits operation Copyright © Atlas Scientific LLC r 0.1...
  • Page 22 NEVER EXTEND THE CABLE WITH CHEAP JUMPER WIRES! DO NOT CUT THE PROBE CABLE WITHOUT REFERING TO THIS DOCUMENT! Copyright © Atlas Scientific LLC...
  • Page 23 DO NOT MAKE YOUR OWN UNSHIELDED CABLES! ONLY USE SHIELDED CABLES. REFER TO THIS DOCUMENT! Copyright © Atlas Scientific LLC...

  • Page 24: Available Data Protocols

    Available data protocols Default Unavailable data protocols Analog RS-485 Mod Bus 4–20mA Copyright © Atlas Scientific LLC r 0.1...
  • Page 25 UART mode Settings that are retained if power is cut Settings that are retained if power is cut Baud rate Find Calibration Sleep mode Continuous mode Temperature compensation Device name Enable/disable response codes Hardware switch to I C mode LED control Protocol lock Software switch to I C mode...

  • Page 26: Uart Mode

    115,200 Data in TX RX Data out 3.3V – 5.5V Data format Reading Data type floating point Units Decimal places Encoding ASCII Smallest string 4 characters Format string Largest string 40 characters Terminator carriage return Copyright © Atlas Scientific LLC...

  • Page 27: Default State

    Default state Mode UART Baud 9,600 Readings continuous Speed 1 reading per second 1,000 ms Green Cyan Standby Taking reading Transmitting Copyright © Atlas Scientific LLC...

  • Page 28: Receiving Data From Device

    ASCII data string Carriage return <cr> Command Terminator 9,600 baud (default) TX RX 9.560 <cr> Receiver Sender Advanced ASCII: <cr> Hex: 36 30 Dec: 54 48 (TX) (RX) (TX) (RX) (TX) (RX) (TX) (RX) Copyright © Atlas Scientific LLC r 0.1...

  • Page 29: Sending Commands To Device

    2 parts Command (not case sensitive) Carriage return <cr> ASCII data string Terminator TX RX Sleep <cr> Sender Receiver Short Advanced ASCII: <cr> Hex: 65 65 70 Dec: 108 101 101 112 Short Copyright © Atlas Scientific LLC r 0.1...

  • Page 30: Led Color Definition

    LED color definition Cyan Purple White Green Changing Command Find UART standby Taking reading baud rate not understood LED ON +2.2 mA 3.3V +0.6 mA Copyright © Atlas Scientific LLC r 0.1...
  • Page 31 Sleep enter sleep mode/low power pg. 34 Slope returns the slope of the pH probe pg. 28 Status retrieve status information pg. 33 enable temperature compensation pg. 29 25˚C enable/disable response codes pg. 32 enable Copyright © Atlas Scientific LLC...

  • Page 32: Led Control

    LED control Command syntax LED on default <cr> LED off <cr> LED state on/off? <cr> Example Response <cr> <cr> <cr> <cr> ?L,1 ?L,0 <cr> <cr> <cr> <cr> Copyright © Atlas Scientific LLC r 0.1...

  • Page 33: Find

    Send any character or command to terminate find. Find LED rapidly blinks white, used to help find device <cr> Example Response Find <cr> <cr> (TX) (RX) (TX) (RX) (TX) (RX) (TX) (RX) (TX) (RX) (TX) (RX) Copyright © Atlas Scientific LLC r 0.1...

  • Page 34: Continuous Reading Mode

    (2 sec) <cr> pH (n sec) <cr> C,30 <cr> <cr> pH (30 sec) <cr> pH (60 sec) <cr> pH (90 sec) <cr> <cr> <cr> ?C,1 ?C,0 ?C,30 <cr> <cr> <cr> <cr> <cr> Copyright © Atlas Scientific LLC r 0.1...

  • Page 35: Single Reading Mode

    Single reading mode Command syntax takes single reading <cr> Example Response 9.560 <cr> <cr> <cr> 1,000 ms Green Cyan Standby Taking reading Transmitting 800 ms Copyright © Atlas Scientific LLC r 0.1...

  • Page 36: Calibration

    Cal,? device calibrated? <cr> Example Response Cal,mid,7.00 <cr> <cr> Cal,low,4.00 <cr> <cr> Cal,high,10.00 <cr> <cr> Cal,clear <cr> <cr> Cal,? ?Cal,0 ?Cal,1 <cr> <cr> <cr> one point ?Cal,2 ?Cal,3 <cr> <cr> three point two point <cr> Copyright © Atlas Scientific LLC...

  • Page 37: Export/Import Calibration

    6F 6C 20 67 75 79 (10 of 10) Export <cr> <cr> Export *DONE <cr> Disabling *OK simplifies this process Import, n Import, 59 6F 75 20 61 72 (1 of 10) <cr> (FIFO) Copyright © Atlas Scientific LLC r 0.1...

  • Page 38: Slope

    99.7% is how closely the 100.3% is how closely the slope of the acid calibration slope of the base calibration line matched the “ideal” matches the “ideal” pH pH probe. probe. 0.3% from ideal 0.3% from ideal Copyright © Atlas Scientific LLC r 0.2...

  • Page 39: Temperature Compensation

    <cr> This is a new command for firmware V2.12 Example Response T,19.5 <cr> <cr> RT,19.5 <cr> <cr> 8.91 <cr> ?T,19.5 <cr> <cr> <cr> T,19.5 <cr> 8.82 8.91 Copyright © Atlas Scientific LLC r 0.2...

  • Page 40: Naming Device

    10 11 12 13 14 15 16 Name,? show name <cr> Up to 16 ASCII characters Example Response Name,zzt <cr> <cr> Name,? ?Name,zzt <cr> <cr> <cr> Name,zzt Name,? <cr> Name,zzt <cr> <cr> Copyright © Atlas Scientific LLC r 0.1 r 0.1...

  • Page 41: Device Information

    Device information Command syntax device information <cr> Example Response ?i,pH,1.98 <cr> <cr> <cr> Response breakdown 1.98 Device Firmware Copyright © Atlas Scientific LLC r 0.1...

  • Page 42: Response Codes

    *OK,? ?*OK,1 ?*OK,0 <cr> <cr> <cr> Other response codes unknown command over volt (VCC>=5.5V) These response codes under volt (VCC<=3.1V) cannot be disabled reset boot up complete, ready entering sleep mode wake up Copyright © Atlas Scientific LLC r 0.1...

  • Page 43: Reading Device Status

    Vcc pin and reason for last restart <cr> Example Response Status ?Status,P,5.038 <cr> <cr> <cr> Response breakdown ?Status, 5.038 Reason for restart Voltage at Vcc Restart codes powered off software reset brown out watchdog unknown Copyright © Atlas Scientific LLC r 0.1...

  • Page 44: Sleep Mode/Low Power

    <cr> Example Response Sleep <cr> Any command wakes up device <cr> STANDBY SLEEP 16 mA 1.16 mA 3.3V 13.9 mA 0.995 mA Sleep <cr> Standby Sleep 16 mA 1.16 mA Copyright © Atlas Scientific LLC r 0.1...

  • Page 45: Change Baud Rate

    <cr> 1200 2400 9600 default 19200 38400 57600 115200 Baud,38400 <cr> (reboot) Standby Standby Changing Cyan Purple White Green baud rate Changing Command Find RT standby Taking reading <cr> baud rate not understood Copyright © Atlas Scientific LLC r 0.1...

  • Page 46: Protocol Lock

    Purple Cyan Purple White <cr> cannot change to I cannot change to I <cr> Changing Command Changing Find Comma ding UART standby Taking reading baud rate not understood baud rate not under Short Copyright © Atlas Scientific LLC r 0.1...

  • Page 47: Factory Reset

    Clears calibration Command syntax LED on "*OK" enabled Factory enable factory reset <cr> Example Response Factory <cr> <cr> Factory <cr> (reboot) <cr> <cr> <cr> Baud rate will not change 1,000 ms 1,000 ms Copyright © Atlas Scientific LLC r 0.1...

  • Page 48: Change To I 2 C Mode

    > 127 <cr> <cr> I2C,100 (reboot) Green Blue Green Green Cyan Cyan Purple <cr> now in I C mode Changing Chan UART standby UART standby Taking reading Taking reading baud rate baud Copyright © Atlas Scientific LLC r 0.2...

  • Page 49: Manual Switching To I 2 C

    • Disconnect ground (power off) Reconnect all data and power • Manually switching to I C will set the I C address to 99 (0x63) Example Short Wrong Example Short Disconnect RX line Copyright © Atlas Scientific LLC r 0.1...
  • Page 50 Settings that are retained if power is cut Settings that are retained if power is cut The I C protocol is considerably more complex than the UART (RS–232) protocol. Atlas Scientific assumes the embedded Baud rate Find systems engineer understands this protocol. Calibration Sleep mode Continuous mode...

  • Page 51: I 2 C Mode

    100 – 400 kHz 4.7k resistor may be needed (TX) (RX) Data format Reading Data type floating point Units Decimal places Encoding ASCII Smallest string 4 characters Format string Largest string 399 characters (TX) (RX) (TX) (RX) Copyright © Atlas Scientific LLC...

  • Page 52: Sending Commands

    99 (0x63) Write Sleep Stop C address Command (TX) (RX) (TX) Advanced Address bits The entire command as ASCII with all arguments First letter of command Last letter of command Start Stop = low Copyright © Atlas Scientific LLC r 0.1...

  • Page 53: Requesting Data

    Null = High Address bits N bytes of data A6 − A0 Response code Data Data N Null Null Start Stop NACK 57 46 53 54 48 = 9.560 ASCII Copyright © Atlas Scientific LLC r 0.1...

  • Page 54: Response Codes

    I2C_address; I2C_write(EZO_command); (TX) (RX) Response codes I2C_stop; Single byte, not string delay(300); Processing delay no data to send still processing, not ready I2C_start; I2C_address; syntax error Char[ ] = I2C_read; successful request I2C_stop; Copyright © Atlas Scientific LLC r 0.2...

  • Page 55: Led Color Definition

    LED color definition (TX) (RX) (TX) (RX) (TX) (RX) (TX) (RX) Blue Green Purple White C standby Taking reading Changing Command Find C ID# not understood LED ON +2.2 mA 3.3V +0.6 mA Copyright © Atlas Scientific LLC r 0.1...
  • Page 56 57 returns a single reading pg. 49 Sleep enter sleep mode/low power pg. 56 Slope pg. 52 returns the slope of the pH probe Status retrieve status information pg. 55 temperature compensation pg. 53 Copyright © Atlas Scientific LLC...

  • Page 57: Led Control

    L,1 LED on default L,0 LED off LED state on/off? Example Response Wait 300ms Null Null Wait 300ms ?L,1 ?L,0 ASCII Null ASCII Null Wait 300ms (TX) (RX) (TX) (RX) (TX) (RX) (TX) (RX) Copyright © Atlas Scientific LLC r 0.1...

  • Page 58: Find

    Send any character or command to terminate find. Find LED rapidly blinks white, used to help find device (TX) (RX) (TX) (RX) (TX) (RX) Example Response Find Wait 300ms Null (TX) (RX) (TX) (RX) (TX) (RX) Copyright © Atlas Scientific LLC r 0.1...

  • Page 59: Taking Reading

    900ms R return 1 reading Example Response 9.560 ASCII Null Wait 900ms (TX) (RX) (TX) (RX) (TX) (RX) Wait 900ms Green Blue Taking reading Transmitting Standby Short (TX) (RX) (TX) (RX) (TX) (RX) Copyright © Atlas Scientific LLC r 0.1...

  • Page 60: Calibration

    Wait 900ms Cal,low,4.00 Null Wait 900ms Cal,high,10.00 Null Wait 900ms Cal,clear Null Wait 300ms ?Cal,0 ?Cal,1 Cal,? ASCII Null ASCII Null Wait 300ms one point ?Cal,2 ?Cal,3 ASCII Null ASCII Null two point three point Copyright © Atlas Scientific LLC...

  • Page 61: Export/Import Calibration

    65 20 61 20 63 6F (10 of 10) Export ASCII Null Wait 300ms *DONE Export ASCII Null Wait 300ms Import, 59 6F 75 20 61 72 (1 of 10) Import, n ASCII (FIFO) Copyright © Atlas Scientific LLC r 0.1...

  • Page 62: Slope

    100.3% is how closely the slope of the acid calibration slope of the base calibration line matched the “ideal” matches the “ideal” pH pH probe. probe. 0.3% from ideal 0.3% from ideal Copyright © Atlas Scientific LLC r 0.1 r 0.1...

  • Page 63: Temperature Compensation

    RT,n set temperature compensation and take a reading This is a new command for firmware V2.12 Example Response T,19.5 Null Wait 300ms RT,19.5 8.91 ASCII Null Wait 900ms ?T,19.5 Wait 300ms ASCII Null T,19.5 8.82 8.91 Copyright © Atlas Scientific LLC r 0.2...

  • Page 64: Device Information

    Device information Command syntax processing delay 300ms i device information Example Response ?i,pH,1.98 ASCII Null Wait 300ms Response breakdown 1.98 Device Firmware Copyright © Atlas Scientific LLC r 0.1...

  • Page 65: Reading Device Status

    Status voltage at Vcc pin and reason for last restart Example Response Status ?Status,P,5.038 ASCII Null Wait 300ms Response breakdown ?Status, 5.038 Reason for restart Voltage at Vcc Restart codes powered off software reset brown out watchdog unknown Copyright © Atlas Scientific LLC r 0.1...

  • Page 66: Sleep Mode/Low Power

    Sleep no response issuing sleep command. Any command wakes up device STANDBY SLEEP 16 mA 1.16 mA 3.3V 13.9 mA 0.995 mA (TX) (RX) (TX) (RX) (TX) (RX) (TX) (RX) Sleep Standby Sleep Copyright © Atlas Scientific LLC r 0.1...

  • Page 67: Protocol Lock

    Wait 300ms Short Short Short Plock,1 Baud, 9600 (TX) (TX) (RX) (RX) (TX) (RX) (TX) (TX) (RX) (RX) (TX) (RX) (TX) (TX) (RX) (RX) (TX) (RX) cannot change to UART cannot change to UART Copyright © Atlas Scientific LLC r 0.1...

  • Page 68: I 2 C Address Change

    CPU until the CPU is updated with the new I C address. Default I C address is 99 (0x63). I2C,100 (TX) (RX) (TX) (RX) (TX) (RX) (reboot) Copyright © Atlas Scientific LLC r 0.2...

  • Page 69: Factory Reset

    Factory reset will not take the device out of I C mode. Factory enable factory reset C address will not change Example Response Factory device reboot Clears calibration LED on Response codes enabled Factory (TX) (RX) (TX) (RX) (TX) (RX) (reboot) Copyright © Atlas Scientific LLC r 0.1...

  • Page 70: Change To Uart Mode

    Green Green Purple Purple Blue Green White mode C standby C standby Taking reading Taking reading Changing Changing C standby Command Command Taking reading Find C ID# C ID# not understood not understood Copyright © Atlas Scientific LLC r 0.1...

  • Page 71: Manual Switching To Uart

    Taking reading Transmitting Standby • Disconnect ground (power off) Reconnect all data and power • Example Short (TX) (RX) (TX) (RX) (TX) (RX) Wrong Example Short Disconnect RX line (TX) (RX) (TX) (RX) Copyright © Atlas Scientific LLC r 0.1...

  • Page 72: Circuit Footprint

    Delete the 8 position header. The two 3 place a 8 position header. top and bottom of the 8 position. position headers are now 17.78mm (0.7”) apart from each other. 1.05mm Ø 17.78mm (0.7”) Copyright © Atlas Scientific LLC r 0.1...

  • Page 73: Datasheet Change Log

    Revised definition of response codes on pg 44. Datasheet V 4.4 Added resolution range to cover page. Datasheet V 4.3 Revised isolation information on pg 9. Datasheet V 4.2 Revised Plock pages to show default value. Copyright © Atlas Scientific LLC...
  • Page 74 Added new feature to continous mode "C,n" pg 24. Datasheet V 4.0 Added accuracy range on cover page, and revised isolation info on pg. 10. Datasheet V 3.9 Revised calibration theory on pg. 7. Datasheet V 3.8 Revised entire datasheet. Copyright © Atlas Scientific LLC...
  • Page 75 V2.11 – (June 12, 2017) • Fixed "I" command to return "pH" instead of "PH". V2.12 – (April 16, 2018) • Fixed “cal,clear” was not clearing stored calibration in EEPROM. • Added “RT” command to Temperature compensation. Copyright © Atlas Scientific LLC...

  • Page 76: Warranty

    ™ circuit (which ever comes first). The debugging phase The debugging phase as defined by Atlas Scientific is the time period when the EZO ™ ™ class pH circuit is inserted into a bread board, or shield. If the EZO class pH circuit is ™...
  • Page 77 EZO class pH circuits continued ™ ™ operation. This is because that would be equivalent to Atlas Scientific taking responsibility ™ over the correct operation of your entire device. Copyright © Atlas Scientific LLC...

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