TEMP05 Frequently Asked Questions

Parasitic Power is a term developed by Dallas Semiconductor to describe their method of powering their "1-Wire" devices. The DS18S20 sensor used by the TEMP05 is one of these 1-Wire devices. As the term implies, there is only one wire (well, 2 really. A ground is also required) used to communicate on a bus with all devices. The power is derived from the communication line. Whenever a logic "1" is sent on the 1-Wire bus, all devices on the bus use that logic "1" to charge up their internal circuitry. Providing that a logic "1" is sent often enough, that charge is sufficient to drive the individual devices. Fortunately, the idle state of the bus is a logic 1, so, statistically, a logic 1 is present very often.

2. Do I need a Dallas Weather Station to use the TEMP05?

No. TEMP05 can be used with any combination of the following devices on the 1-Wire bus;

Dallas or AAG 1-Wire Weather Station (one only)
DS18S20 temperature sensors
DS1820 temperature sensors
DS18B20 temperature sensors
DS1822 temperature sensors
DS1920 temperature sensors
DS2405 switch sensors
DS2406 switch sensors
DS2407 switch sensors
DS2401 1-wire ID sensors
DS2423 based Rain Gauge
DS2423 based Lightning detector
DS2423 general purpose counter
DS2438 based Humidity Sensors
DS2438 based Barometer
DS2438 voltage monitors
None of the above (why would I do that? TEMP05 can also be used to drive a companion device called RELAY05 without needing any sensors)

3. How do I connect the temperature sensors to the TEMP05?

The sensors are connected via twisted pair wire, typically CAT-5 or better, to connector J2. The external wire can be "home run" (all sensors connected on their own wire and all end-points tied together), or daisy-chained (one, or more, wire runs are used and each sensor is "tapped" into the wire run where needed). The sensors themselves are then soldered on to the wire run wherever they are needed. If you don't like soldering these devices, some people have had success with crimping the sensors into RJ-11 plugs and running wires to RJ-11 sockets where the sensors are needed. Midon Design also provides small PCB mounts for attaching a DS18S20 sensor and either a RJ-11 connector or 2 terminal screw connector. They are shown here.

NOTE: if you are using parasitic power, you must connect the ground wire to both outer pins of the DS18S20 to ensure reliable readings.

4. Can I daisy-chain temperature sensors?

Yes. They can be wired into anywhere along the wire run from TEMP05. A termination is not required at the end of the wire run when daisy-chaining, although care should be taken to avoid shorting out the end point.

5. How far away can the temperature sensors be run?

Using good quality CAT-5 cable, you should be able to run sensors up to 300 feet (100 meters) away from the TEMP05.

6. Where do I get a Weather Station?

The original manufacturer (Dallas Semiconductor) no longer makes this product. One manufacturer Tecnologia Aplicada (AAG) has replicated the original design (see also question 19). Another source of similar product is Texas Weather Instruments Inc. . Midon Design has verified functionality of Technoligia Aplicada and Dallas Semiconductors products with the TEMP05.

7. How does TEMP05 connect to my PC?

A straight-through, not null modem, serial cable connects between the TEMP05 and your PC's serial port. The signal is 9600 bps, no parity, eight bits, with NO flow control. Hyperterminal can be used to monitor output from the TEMP05, or to configure it. See also #17. Here is an example of a serial cable that could be used to connect to your PC.

8. Can the sensors be used in water (pools, fish tanks, spas, etc.)?

Yes, although care must be taken to ensure that the connections to the sensor, and the sensor leads, are properly water-proofed. Silicon RTV or epoxy could be used to accomplish this.

9. How can I tell which sensor is in which area?

The recommended method is to connect one sensor at a time, run the INI command on TEMP05 and then record the newest serial number found in the list displayed by the DIS command. That serial number will appear in the sensor output if the SID ON command has been issued.

Alternatively, all sensors can be pre-configured. Attach each sensor one at a time. Note which sensor output value changes from "???" to a valid temperature reading after attaching a new one. That is your new sensor.

If you have already installed all your sensors, just disconnect each one individually and look for the sensor that changes value from a valid temperature reading to "???".

With Version 5 and higher software, TEMP05 will notify you real time as you connect and disconnect temperature sensors, providing that the sensor had initially been registered with TEMP05 via the INI command.

10. What do I use for power?

Just about any power adapter can be used with the TEMP05. If your are NOT using the companion RELAY05 module, then you can look through your discarded wall adapters from old electronic devices for something that is rated at least 9 Volts (AC or DC) and at least 100mA (milli-Amperes). If you are using RELAY05 with TEMP05, then your adapter needs to be between 12 and 15 Volts with at least 800mA current capability.

11. What do I need to read temperatures from a few different rooms?

For example, to get temperature readings from 3 different areas you will need;

1 TEMP05 (assembled and tested)
3 DS18S20 Sensors
1 12VAC or DC adapter (available from Radio Shack, Best Buy, etc. or from midon design)

All items are on the ordering page.

The TEMP05 connects to your PC via a spare serial port. You will need a straight-through serial cable, not a null modem cable, to connect TEMP05 to your PC. An example cable would be Radio Shack's 26-117.

A sample HomeSeer script is available from the TEMP05 web page.

Note: if one of the temperatures you want to sense is in the same area as where you will place the TEMP05, then you will only need one extra sensor since there is one already built onto the TEMP05 board.

12. Do I have to use HomeSeer to read the temperatures?

No. Any PC application that reads the serial port can be used. HomeSeer provides some simple to use script and plug-in interfaces to the serial port, however.

13. Will TEMP05 work with a serial to USB converter?

Yes. TEMP05 has been successfully tested with a Belkin F5U103 USB Serial Adapter.

14. Will TEMP05 work with a Humidity Sensor?

Yes! V4.14 firmware and higher will read humidity from multiple DS2438 Humidity sensors from Midon Design, AAG or Hobby Boards.

15. Is there an enclosure for the TEMP05?

Not yet. We are re-designing the PCB to fit into a standard PacTec CM5-125 enclosure. Until we release this new PCB, please go here for alternate suggestions on how to enclose the TEMP05 board.

16. What are the differences between a DS1820 and a DS18S20?

The document here describes this best. Basically, the DS18S20 has superior temperature accuracy and a wider power supply tolerance.

17. How do I set up HyperTerm to talk to TEMP05?

Correct settings in HyperTerminal are:

9600 baud
8 bits
no parity
1 stop bit
NONE for flow control (Important!)

18. How do I set-up HomeSeer to use the readings from TEMP05?

Follow the instructions here.

19. What is the difference between a Version 1 and a Version 3 One Wire Weather Station?

The Version 1 OWWS is the original unit developed and sold by Dallas Semiconductor. Is is electrically equivalent to the Version 2 OWWS sold by AAG, a Mexican company. AAG improved the design to replace the DS2401-based wind direction sensors with a new DS2450-based design and are now selling it as the Version 3 OWWS. TEMP05 firmware V4 will work with the Version 3 or Version 1 or Version 2 OWWS. TEMP05 V5.00 and higher firmware no longer supports the Version 1 OWWS, however.

20. I ordered DS18S20's, but the items I received are labeled DS1820. What gives?

Dallas/Maxim have chosen not to label the DS18S20's with the "S". This may be due to the fact that they have discontinued the original DS1820 package and assumed that there would be no confusion. The DS1820 stopped production around May 2000. The only visible difference is the package style. The DS1820 was in a PR-35 package, whereas the DS18S20 is in a standard TO-92 package. See FAQ #16 for the electrical differences.

21. Will TEMP05 work with DS18B20, DS1920 and DS1822 temperature sensors?

Absolutely! You will need V4.21 or higher software to read the DS18B20 and DS1822 sensors. DS1920 sensors are identical to DS1820 sensors and can be read with any version of TEMP05.

22. I am using V4.19 (or higher) and my weather station stopped providing the wind direction (gives ???). Why?

The ??? is used to display incorrect readings. While there are several possibilities for this, faulty sensors for example, there is one likelier problem with 4.19 or higher software. The NOR command, which is used to calibrate the wind direction sensor(s), stores the calibration results in one of your DS1820 sensor's EEPROM memory. If you have removed the DS1820 sensor that had that information stored, or did an ERA and INI command, then the software will read incorrect calibration results and error out on the direction. Try re-doing the NOR command and see if that helps.

This problem is not evident with V5 software.

23. I added a sensor and now my readings are coming back as "???". Why?

You might have added a the sensor via a new wire leg in a star configuration. This might have created reflections on the One Wire bus. Try adding a 100 ohm resistor (Radio Shack part number 271-1311) in series with each leg of the star (only on the DQ lead). The figure below shows how the wiring should be done for this.

24. Where can I buy a Humidity Sensor?

Midon Design sells a 1 Wire Humidity Sensor as part number MD3020E. They were originally available from Dallas/Maxim, however, Dallas/Maxim announced the discontinuation of this product. An alternate source is Hobby Boards. Go to this link to view the Midon Design version. AAG also sells a humidity sensor, however, it is only available in parasitic power mode.

25. My outdoor temperature sensor appears to be inaccurate. What can I do?

Exposure to direct sunlight can affect the sensors - they read too high. A solution for this is to put the sensors in a "pagoda". Construction articles are shown on the following links:

http://www.dpug.org/weather/newpagoda.html

More discussion here: HomeSeer TEMP05 Messages

26. I connected a sensor to the board. How do I get it recognized?

From a HyperTerminal session, issue an INI command. This will find the new sensor and add it's serial number to EEPROM memory. There is no need to do an ERA command, which will erase all the EEPROM memory, unless you want to delete some or all of the other sensors that were previously recognized. The new sensor(s) added by the INI command are automatically added to the next available (usually the last) memory position.

27. Does TEMP05 interface with the SHT11/71 humidity sensor?

No. We have looked into using the SHT (Sensirion) sensor series but decided that the 2 wire interface used to connect to it was not conducive to remote applications like the One Wire bus is used for.

28. How do I connect sensors around the house?

Please see an excellent discussion about this on the HomeSeer message board here.

29. How do I connect a DS2405, DS2406 or DS2407 to other components?

The following schematic is good for any of the DS2405, DS2406 or DS2407 1-wire devices. As can be seen, the PIO port can be used for switch (or contact closure) inputs, or as an output to drive LED's, relays, or other devices.

30. What are the pins used for on the RJ11/12 connectors?

Here is a table of all published connector schemes for various 1-wire devices:

Device	Pin 1	Pin 2	Pin 3	Pin 4	Pin 5	Pin 6
Dallas/Maxim wiring standard	+5VDC	GND	DQ	GND	N/C	DC Supply
Midon Design MD2004 TEMP05	N/C	+5VDC	DQ	GND	N/C	N/C
Midon Design MD2104 TEMP08	DC Supply	+5VDC	DQ	GND	N/C	N/C
Midon Design MD3009 Temp Sensor	N/C	+5VDC	DQ	GND	N/C	N/C
Midon Design MD3020 Temp and Humidity Sensor	DC Supply	+5VDC	DQ	GND	N/C	N/C
Midon Design MD3021 Relay and LED Sensor	DC Supply	+5VDC	DQ	GND	N/C	N/C
Simon Atkin's Hub	+5VDC	DC Supply	DQ	GND	DC Supply	GND
AAG TAI8550 Combo Switch	+5VDC	GND	DQ	GND	N/C	N/C
AAG TAI8520 Temp Sensor	+5VDC	GND	DQ	GND	N/C	N/C
AAG V3 1-Wire Weather Station	N/C	+5VDC	DQ	GND	GND	N/C
AAG TAI8540A Humidity Sensor	N/C	N/C (GND?)	DQ	GND	N/C (+5VDC?)	N/C
AAG TAI8555 Latch Relay	N/C	GND	DQ	GND	N/C	N/C
AAG TAI8585 Counter Kit	N/C	N/C	DQ	GND	N/C	N/C
AAG DS9097U-S09-X	N/C	GND	DQ	GND	+5V	N/C

The pin numbers are numbered per the diagram here.

Download the PDF version of this table here.

31. How do I use HomeSeer to activate relays on RELAY05?

There are 2 ways of doing this. If you are using Ken Mitchell's TEMP05 plug-in, activate relays from the HomeSeer web page, or GUI, simply by pressing one of the relay On/Off buttons. This can also be accomplished via a script by using the following command:

hs.execx10 "[x","on",0 where x is the relay number and [ is the relay house code

If you are not using the TEMP05 plug-in, then use a script with the following command to activate a relay:

hs.SendToComPort 1,"rlyxon" where x is the relay number

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Last Updated January 1, 2020

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