> For the complete documentation index, see [llms.txt](https://docs.aethlabs.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.aethlabs.com/microaethalometer-tm-ma600/manual/instrument-settings.md).

# 6. Instrument Settings

Configurable settings for the microAethalometer™ MA600 — timebase, flow rate, DualSpot/SingleSpot mode, wavelengths, tape advance, RS-232 serial, AutoSample, time synchronization, and recommended sett

## 6.1 Settings Overview

Settings can be configured through:

* **microAeth® Manager software** (USB connection, recommended): All settings configurable. See [Chapter 7: microAeth Manager Software](https://docs.aethlabs.com/microaethalometer-tm-ma600/manual/pages/6rxWlVGc1QCXvhFlnucJ#id-7.3-configuring-settings-via-software) §7.3.
* **On-board user interface** (3-button interface): Subset of settings accessible. See [Chapter 8: On-Board Operation](https://docs.aethlabs.com/microaethalometer-tm-ma600/manual/pages/Ih2DrJl96GAEm7I3ctnc#id-8.2-menu-navigation) §8.2.
* **Serial command interface** (CLI): Settings readable and writable via AethLabs serial protocol commands over the RS-232 DB-9 connection. See [Chapter 9: Data Management](https://docs.aethlabs.com/microaethalometer-tm-ma600/manual/pages/XkOnqlVBs8XTUOoUNENj#id-9.6-serial-output-protocol) §9.6.

**Settings are stored in non-volatile memory.** They persist across power cycles. Review settings after firmware updates.

## 6.2 Timebase

The timebase sets the measurement interval in seconds. Each timebase period produces one row of data.

**Available timebases:** 1, 5, 10, 30, 60, or 300 seconds.

**Selection guide:**

| Application                      | Recommended timebase  |
| -------------------------------- | --------------------- |
| High-concentration / near-source | 10–30 seconds         |
| Fixed monitoring station         | 30–60 seconds         |
| Background / low-concentration   | 60–300 seconds        |
| Maximum data storage duration    | 300 seconds → longest |

{% hint style="success" %}
**Recommendation:** For continuous stationary deployment, start with a **60 second** timebase (or longer) and adjust based on your application.
{% endhint %}

**Effect on filter tape life:** Shorter timebases mean more data per unit time but do not affect how quickly the filter loads. Filter life is determined by aerosol mass concentration and flow rate, not timebase.

## 6.3 Flow Rate

The flow rate setpoint controls the volumetric flow drawn through the instrument by the BLDC pump.

**Available settings:** 100–250 ml/min.

**Default (recommended):** 150 ml/min.

**DualSpot® compatibility:** Not all flow rates are compatible with every DualSpot® configuration. At lower flow rates, the secondary spot (Spot 2 / sense2) may not achieve minimum required flow. The firmware will report a flow calibration warning if the setpoint is outside calibrated range. A flow rate of 100 ml/min or greater is recommended when using DualSpot®.

**Effect on filter tape life:**

* Higher flow rates load the filter faster; filter advances more frequently
* Lower flow rates extend filter tape life but reduce sensitivity at low concentrations

**Effect on sensitivity (limit of detection):**

* Higher flow rates improve sensitivity (more aerosol per unit time), but also use more filter tape and more power

## 6.4 DualSpot® vs. SingleSpot™

| Factor                 | DualSpot®                                                               | SingleSpot™                                                        |
| ---------------------- | ----------------------------------------------------------------------- | ------------------------------------------------------------------ |
| Loading compensation   | Yes — real-time K correction                                            | No                                                                 |
| Source apportionment   | Enabled (with IR + Blue wavelengths, at minimum)                        | Disabled                                                           |
| Flow split             | Two spots — 75% Spot 1 (sense1) / 25% Spot 2 (sense2), 150 ml/min total | Single spot at full flow                                           |
| BC accuracy in high PM | Significantly better                                                    | Degrades as filter loads                                           |
| BC accuracy in low PM  | Equivalent                                                              | Equivalent                                                         |
| Data columns           | BC1, BC2, BCc, K per wavelength                                         | BC1 only per wavelength                                            |
| Recommended for        | Most applications                                                       | Low-PM environments only or when flow constraints prevent DualSpot |

{% hint style="success" %}
**Recommendation:** Use DualSpot® for all applications unless you have a specific reason to use SingleSpot™. DualSpot® improves data quality in all but very low PM environments and enables source apportionment.
{% endhint %}

**Switching modes:** Change in microAeth Manager. The instrument must be stopped; restart after changing mode. The on-board test flow screen also differs between modes.

## 6.5 Wavelength Selection

By default all five wavelengths are active. Individual wavelengths can be disabled in microAeth Manager.

**Reasons to disable wavelengths:**

* Source apportionment not needed: Can disable UV channel to reduce filter tape usage
* Maximum tape life: Operating with the IR channel only increases tape life by at least 2.3× compared to all five wavelengths enabled, providing Black Carbon quantification only
* Specific research protocols requiring a subset of wavelengths

{% hint style="info" %}
Source apportionment requires the IR + Blue wavelengths (at minimum) and DualSpot® enabled. Status code 4096 (S.A. disabled) will appear if Source Apportionment is attempted with insufficient wavelengths active.
{% endhint %}

Current wavelengths shown in Display All Settings output: `IR R G B UV` (all enabled).

## 6.6 Tape Advance ATN Threshold

The ATN threshold controls when the instrument automatically advances the filter tape to a new clean sampling location.

**Default:** 50 attenuation units.

**Range:** 1–100 attenuation units.

**How it works:** When the attenuation of the most-loaded wavelength channel reaches the threshold value, the instrument performs an automatic tape advance at the next measurement interval boundary.

**Threshold selection guidance:**

| Environment                  | Suggested ATN threshold                                      |
| ---------------------------- | ------------------------------------------------------------ |
| High PM (urban, near source) | 30–50 — tape advances more frequently; protects data quality |
| Low PM (background)          | 50–75 — extends tape life                                    |
| Maximum data quality         | 30–40 — more frequent advances, more tape used               |
| Maximum tape life            | 70–100 — use only in very clean environments                 |

{% hint style="info" %}
The lowest wavelength enabled (UV at 375 nm) typically reaches the threshold first because UV absorbs more strongly from organic PM. With SingleSpot™, a threshold of 50 (with UV enabled) usually minimizes loading effects.
{% endhint %}

## 6.7 RS-232 Serial Settings

The MA600 outputs data and accepts commands over the RS-232 DB-9 **SERIAL** connector using the MA Series serial protocol. See [Chapter 9: Data Management](https://docs.aethlabs.com/microaethalometer-tm-ma600/manual/pages/XkOnqlVBs8XTUOoUNENj#id-9.6-serial-output-protocol) §9.6 for the full command set and data-line format.

| Setting      | Options                                 |
| ------------ | --------------------------------------- |
| Baud rate    | Default 1,000,000; configurable via mAM |
| Data bits    | 8                                       |
| Parity       | None                                    |
| Stop bits    | 1                                       |
| Flow control | Xon-Xoff                                |
| Data format  | Verbose / Standard                      |
| Streaming    | Enabled / Disabled                      |

Serial data output begins automatically when sampling starts. Use RS-232 for integration with data acquisition systems, loggers, and SCADA.

## 6.8 Time Synchronization

The MA600 does not include GPS. The instrument clock is set manually from a connected computer through microAeth Manager.

**Setting the clock:** Connect the instrument to microAeth Manager and synchronize the clock to the computer time. When the time source is manual, the Time Source field reads "Manual" and status code 512 (Time source manual) appears in the data.

**Timezone offset:** Set in minutes from UTC (e.g., −480 for UTC−8, −420 for UTC−7). All timestamps in the data file are recorded in UTC; the timezone offset is stored as a separate field so post-processing software can display local time.

## 6.9 AutoSample

AutoSample determines whether the MA600 starts sampling on its own when power is applied. The current setting is shown on the display and in the serial output during the startup sequence, for immediate verification.

{% hint style="info" %}
Each automatic start begins a new session, which advances the filter tape and restarts the ATN measurement from zero.
{% endhint %}

Options:\
**Off** - The MA600 never starts sampling on its own. With AutoSample off, applying power does not boot the instrument up ready to use: it powers on into a standby sleep state. Press any button to wake it.

**After power fail** - The MA600 resumes sampling if it was sampling when power was lost. A session that was stopped deliberately stays stopped, and the instrument goes to sleep as above. Use this where an operator starts each session and the instrument should automatically sample after a power interruption.

**Always on power up** - The MA600 begins sampling every time power is applied, whether or not it was sampling before. Each power-up begins a new session, which advances the filter tape and restarts the ATN measurement.

## 6.10 Recommended Settings by Scenario

<details>

<summary>Recommended Settings by Scenario (Timebase, Flow, Mode, ATN)</summary>

| Scenario                   | Timebase | Flow       | Mode       | ATN threshold |
| -------------------------- | -------- | ---------- | ---------- | ------------- |
| Fixed monitoring station   | 60 s     | 150 ml/min | DualSpot   | 50            |
| Background / low PM        | 60–300 s | 150 ml/min | DualSpot   | 75            |
| High PM / near-source      | 10–30 s  | 150 ml/min | DualSpot   | 30–40         |
| Low-PM / clean environment | 60–300 s | 150 ml/min | SingleSpot | 50            |

</details>

## 6.11 Best Use Practices

The versatility of the microAethalometer allows it to gather data in a wide range of operational scenarios. Optimization of performance across the breadth of applications requires an understanding of scientific objectives, operational settings, their impact on instrumental sensitivity and trade-offs, as well as proper maintenance of the instrument. The following recommendations provide general guidelines.

### 6.11.1 Measurement Timebase and Flow Rate

To get the best data from the MA600 for a sampling campaign, we highly recommend that the instrument warm up for approximately 30 minutes so that it can equilibrate. The microAethalometer can acquire data on six timebase settings: 1, 5, 10, 30, 60, or 300 seconds. The 1 second timebase should only be used under special circumstances where a decreased signal-to-noise ratio is acceptable. At this setting, instrumental noise is larger and typically requires post-processing. The MA600 pump can operate across a flow range of 100–250 ml/min. The choice of these parameters affects the operation and data. On a 1 second timebase, the instrument will acquire a large volume of data per day, which may be more challenging to handle and take longer to download. Due to the flow split between Spot 1 and Spot 2, the measurement sensitivity in DualSpot® mode will be lower than in SingleSpot™ mode for the same total flow rate.

### 6.11.2 Effects of Contamination

**Effects of Contamination, Vibration, and Impact:** Primarily affected by timebase setting.

<details>

<summary>Effect of Contamination, Vibration, and Impact by Timebase</summary>

| 1 second   | 5 seconds | 10 seconds | 30 seconds | 60 seconds | 300 seconds |
| ---------- | --------- | ---------- | ---------- | ---------- | ----------- |
| very large | large     | large      | moderate   | low        | least       |

</details>

If the sample chamber becomes contaminated, or the MA600 instrument experiences large vibration or impact, the data may be degraded. A "dirty" instrument may be more succeptible to data excursions and these effects are amplified greatly at shorter timebase settings. This is most relevant if the device is used in a mobile application such as in a vehicle.

### 6.11.3 Recommended Cleaning & Maintenance Intervals

It is suggested to perform standard maintenance on the MA600 at least once per 12–18 months. Unique, dirtier, and/or higher concentration sampling environments and applications may require standard maintenance on more regular intervals. It is recommended that users plan standard maintenance schedules that best coincide with and allow for the best data quality during measurement campaigns. See [Chapter 10: Calibration & Maintenance](/microaethalometer-tm-ma600/manual/calibration-maintenance.md).

### 6.11.4 microCyclone™ PM2.5 Size-selective Inlet

The microCyclone™ 170 may help to prevent contamination in dusty or dirty environments where larger diameter particles are present. The microCyclone™ PM2.5 size-selective inlet can be connected to the inlet of the MA600 to provide a PM2.5 size cutpoint at the appropriate flow rate. The microCyclone may not be appropriate for use with the MA600 at every operating setting depending on flow rate and whether DualSpot® loading compensation is enabled. Contact AethLabs for flow rate compatibility with the MA600 BLDC pump settings.

{% hint style="warning" %}
**IMPORTANT:** If a microCyclone is being used with your MA600, please clean it on a frequent basis, depending on sampling environment and concentrations. Please see the microCyclone manual and documentation for more information.
{% endhint %}

## 6.12 Filter Media

The sample collection and analysis is performed on a roll of polytetrafluoroethylene (PTFE) filter tape that is housed in the filter tape cartridge (MAFT-L85). As the aerosol sample is drawn through the filter media by the instrument's integrated sample pump, the aerosol sample collects gradually on the filter medium to create a gray spot 3 mm in diameter. The MA600 determines the optical attenuation as the accumulated particles increase the optical density of the filter spot. After the optical density reaches a certain level, which is set by the ATN Tape Advance threshold, the filter spot must be replaced to maintain measurement integrity. The filter tape roll is automatically advanced to provide a new clean spot location for sampling. **IMPORTANT: Do not rewind the filter tape cartridge, or use previously sampled filter tape sampling locations.**

The tape position counter increments each time the filter tape cartridge advances. This counter is reset every time the tape clamp mechanism is released and then reclamped. The instrument does not specifically know the position of the filter tape in the filter tape cartridge in relation to the beginning or end of a filter tape cartridge. The user is responsible for keeping track of this process using the counter as a guide. The instrument is able to know and notify the user when a filter tape cartridge has reached the end of the tape.

## 6.13 Data Safety

AethLabs highly recommends exporting and keeping a pristine backup file of the original data collected by the instrument. Download data via the microAeth Manager computer application and export to a local data file for storage.