Barometer/Humidity Sensor

Table of Contents:

Relevant Devices

Description	Qty	Source	Part Number
Barometer/Humidity Sensor	1	Vaisala	PTU300
Serial Interface Cable	1	Vaisala	19446ZZ
RS-232 to Ethernet Adapter	1	Lantronix	UDS2100	This is the version with two serial ports (but standard 9-pin RS-232 connectors)

Relevant Functional Block Diagram

Software Actions

	Action	Notes
1	Read pressure value	Value reported as telemetry (see below)
2	Read temperature value	Value reported as telemetry (see below)
3	Read relative humidity value	Value reported as telemetry (see below)

Required Adjustable Settings

Setting	When Needed			Notes
	Build	Observing	Maintenance
Pressure measurement frequency	Yes	No	Maybe	Set in configuration file. If this needs to be changed, edit configuration file, re-install, and then restart dispatcher.
Temperature measurement frequency	Yes	No	Maybe	See pressure.
Relative humidity measurement frequency	Yes	No	Maybe	See pressure.

Required Telemetry

	Parameter	Report Frequency	Purpose	Notes
1	Pressure measurement	Once every 5 sec [TBC]	Environmental monitoring	Managed through configuration file
2	Temperature measurement	Once every 5 sec [TBC]	Environmental monitoring	See pressure.
3	Relative humidity measurement	Once every 5 sec [TBC]	Environmental monitoring	See pressure.

Required Alarms

	Parameter	Threshold	Notes
1	Time of last connection	More than 10 seconds
2

Relevant Datasheets & Manuals

Description

File

Source

1

Vaisala PTU300 User’s Guide (2019 version; device purchased in 2014)

https://www.vaisala.com/en/products/instruments-sensors-and-other-measurement-devices/instruments-industrial-measurements/ptu300

2

Lantronix UDS 2100 Quick Start Guide

https://www.lantronix.com/products/uds2100/#tab-docs-downloads

3

Lantronix UDS 2100 User Guide

https://www.lantronix.com/products/uds2100/#tab-docs-downlo

Relevant Software

Description

Files

1

Python 2 software written by a student some years back. These lines of code were used to read values from the Vaisala while it was installed at Keck.

That installation was using a USB interface on a Windows machine. Not sure if the current serial interface will change anything here.

2

As part of the KROOT distribution, there is a SerialStream interface which manages connections to and from serial hosts. This includes managing Lantronix connections.

Dispatcher Implementation

Keyword	Value	Type
CONN	On or Off - controls whether or not the connection to the Lantronix is on or off. Can be used if the Vaisala needs to be unplugged and moved, for example.	Boolean which is writable.
IP	IP address of the Lantronix box.	String set in the configuration file, only readable.
PORT	Port for the Lantronix box that talks to the correct serial device.	String set in configuration file, only readable.
RETVAL	Value returned by Vaisala.	String. The format is set in the configuration file. Only readable.
TIME	Time stamp of when the last RETVAL was received.	Unix timestamp (binary) or time stamp (ascii). Only readable.
PRES	Pressure value in units of hPa.	Double value from RETVAL, read only.
RELH	Relative humidity in %.	Double value from RETVAL, read only.
TEMP	Temperature in deg C.	Double value from RETVAL, read only.
DISPSTA	Dispatcher status.	Enum and read only. If value is 4 or “Not Connected” the connection to the Vaisala or the Lantonix is not available. If value is 3 or “Connecting” the dispatcher is attempting to connect to the Vaisala through the Lantronix.

Configuration	Value	Explanation
ip	192.168.23.102	IP address of the Lantronix box.
port	10001	Port that is used for Vaisala, this is port 1.
format_str	form 9.4 "P=" P " " U6 6.4 "T=" T " " U3 6.4 "RH=" RH " " U4 \r \n	Format statement of the output from the Vaisala. At dispatcher start up and at every new connection, this value is sent to the Vaisala. The #.# sets the number of characters (first # ) and the second # sets the number of characters after the decimal point. There must be a space between the characters that notes what the value is (such as P=) and the actual value (the P). The code uses the characters (P=, RH= or T=) to determine what the next value is.
poll_time	5	Time between reads of the Vaisala in seconds.