Teledyne 651 Data Communication Ports

Instrument Description Teledyne API Ultrafine Particle Monitor - Model 651

40 07506C DCN6727

Data Communication Ports

The Model 651 provides a USB port for communications use.

The Model 651 provides one standard, 9-pin RS-232 serial port that

allows communication between a computer and the particle

monitor. Serial commands are sent to and from the computer to

monitor instrument status information, to retrieve and monitor

data, and to provide a variety of control functions such as turning

the pump on and off. More information can be found in the

Computer Interface section of Chapter 8 in this manual.

The Model 651 can monitor the analog voltage from an external

source via the analog input BNC connector on the back panel

(labeled Analog Input). The input voltage range for these ports is

0 to 10 V. Analog voltages can be displayed together with

concentration data on the display screen and can be saved to the

removable Flash Drive or a computer. Voltages from connected

pressure, flow, or temperature transducers can be correlated to

particle concentration in real time.

Amplification must be supplied by the user to bring low voltage

signals to the appropriate 0 to 10 V range for best resolution.

During normal operation of the Model 651, the Analog Out port

provides an analog 0 to 10 V signal proportional (linear or log) to

particle concentration. This particle concentration is corrected for

coincidence and tracks the displayed concentration.

Pulse Out provides a 5-volt (50-ohm termination) digital pulse for

each particle detected. This enables you to use your own counting

electronics hardware and provides a particle trigger for special

applications. The width of the pulse depends on both the shape of

the photo detector pulse and the trigger-level of the pulse threshold.

To provide accurate pulse counts, use a counter that is capable of

counting pulses with a width of 50 nanoseconds or less.

Particle concentrations that have been calculated based on the

particle counts from the counting electronics hardware are not live-

time corrected for particle coincidence. Thus, when particle

concentration is high, the concentration provided by this output

might be lower than the displayed concentration. Appropriate

coincidence correction should be applied when pulse output is used

for high concentration measurements.