FS-8700-123 – MetOne Particle Counters

FieldServer Driver


HACH Ultra Analytics (formerly Pacific Scientific Instruments) Standard Protocol FX (enhanced) – ENG110

Developed for interfaces to MetOne Particle Counters


The MetOne Particle Counter Serial driver allows the FieldServer to transfer data to and from devices over RS-232 or RS-485 using MetOne Particle Counter Serial protocol.

This driver is based on a specification called “Standard Protocol FX (enhanced)” ENG110 Revision A dated 1999 by Pacific Scientific Instruments. This protocol provides an interface to Particle Counters manufactured by HACH Ultra Analytics and labeled as METONE products. Pacific Scientific Instruments is a former name of Hach.

The primary purpose of the driver is to obtain the current particle counts, but it does allow for limited control and configuration of some counter parameters. While the driver provides Client and Server emulation, the Server side of the driver is intended to support FieldServer’s Quality Assurance program and is not intended to provide complete emulation of a MetOne Counter. Thus the Server side is not fully documented and is not supported. At a customer’s request the Server side functionality can be documented and enhanced. If you are interested in this functionality, then please contact FieldServer’s sales group.

When configured as a Client the driver can start/stop a unit from sampling, change its mode, set and get sample and hold times, startup or standby a unit and retrieve its current sample value. Whenever the driver stores a sample value, it will also store a timestamp of when the record was obtained.

In the configuration of the FieldServer each device is identified by specifying its device number then the sub-device code or port number and finally by a device type. The device type will be used to interpret the status byte obtained from the device.

For each configured node, each time the FieldServer sends a message to the device it will select the device (and the select the sub-device or port if specified) and then the message will be sent. If the most recent message sent was sent to the device, the driver will do the selection to ensure the correct device response. The delay between messages is configurable.

When the current record is read from a device then the driver will store the data extracted from the response in a range of consecutive Data Array elements so that these values can be served to another protocol. Even though the record data contains a time stamp, the driver will make its own time stamp for new data. If there is no current record the driver will not update the data.

If the response is invalid in any way – invalid characters or invalid checksum the driver will ignore the message and not store any data.


Max Nodes Supported


FieldServer mode Nodes Comments
Client 1 There can only be one Client node per FieldServer port. The driver can poll any number of Server nodes provided that they comply with the vendors numbering requirements
Server Driver as a Server is not documented or supported. Used only for QA purposes.


Formal Driver Type


Client Only


Compatibility Matrix

FieldServer Model Compatible with this driver
FS-x2010 Yes
FS-x2011 Yes
FS-x30 Yes
FS-x40 Yes


Connection Information

Connection type: RS-232 and/or RS-485 (Two wire, Half-Duplex)
Baud Rates: 9600 (Vendor limitation).
Data Bits: 8 (Vendor limitation)
Stop Bits: 1 (Vendor limitation)
Parity: None (Vendor limitation)
Hardware interface: None
Multidrop Capability Yes


Devices tested

Device Tested (FACTORY, SITE)
R4803 Remote Particle Counter SITE
2100 Particle Counter with 2432 Manifold with 32 locations. SITE


Connection configurations




Hardware Connection Tips / Hints

The 2100 Device auto configures its serial port based on the pins connected. There is no explicit setting or selector for RS-232/RS-485

Ensure other pins are not connected.

The FS-8917-16 cable is not needed for RS-485 on the X30 and X40 only.


Communications functions – Supported functions at a glance:




Send Buffered Records


We will always read the current record

Send Current Record


Clear Buffer


Query Number of Records


EPROM Number


View Hold Time


Program Hold Time


View Sample Time


Program Sample Time


Query Mode


Re-Transmit Record


Identify Type


Universal Device Select


Protocol Version


Device Select


Sub-Device Select


Set to Auto Sample Mode


Set to Manual Sample Mode


Quick Start Counting


Start Counting


Stop Counting


Set Active Mode


Powers up unit

Set Standby Mode


Powers down unit

Universal Auto Sample Mode


No Universal commands implemented

Universal Manual Sample Mode


Universal Clear Buffer


Universal Quick Start Count


Universal Start Count


Universal Stop Count


Universal Set Active Mode


Universal Set Standby Mode



Unsupported Devices or Protocol Options

The driver cannot be used to control the MetOne 2432 Manifold.

The driver expects that the Particle counters have been correctly configured – it cannot be used to configure the devices. The 2100 Counter in particular must be configured to process each port of interest. The driver does not command the sampling, it only retrieves the data.




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