APPNOTE: Troubleshooting PM2000 and PM1000 communications.
APPNOTE: Troubleshooting PM2000 and PM1000 communications.Last reviewed:May 01, 2008
Article ID: 080429sab
The information in this article applies to:
This article is aimed at:
There are several possible causes of unreliable communications between a PM2000 or PM1000 and Pronto for Windows or PmScreen. The known causes are:
This application note provides details of each cause and suggests solutions.
Problem: Some USB to serial converters do not provide sufficient current on their control lines to power the Actisys IR220L+ Infra red adaptor.
Explanation: The Actisys converter is powered using RS232 control lines (specifically the DTR line). Some converters are unable to provide sufficient power for the Actisys adapter particularly during the "Wakeup" sequence making operation unreliable. During tests it appears that once the voltage on the DTR line drops below 4.0 volts the Actisys adaptor resets and communication with the Logger stops.
Solution: Try using a "real" motherboard mounted 9 pin serial
port instead of a USB to Serial Converter.
An alternative solution using
a direct USB to infra red converter is being investigated by us as of the 1st
May 2008, results on testing will be posted here in the next couple of weeks.
Problem: Some Laptop serial ports do not provide sufficient power for the Actisys IR220L+ Infra red adaptor.
Explanation: The Actisys converter is powered using RS232 control lines (specifically the DTR line). Some laptops are unable to provide sufficient power for the Actisys adapter particularly during the "Wakeup" sequence making operation unreliable. During tests it appears that once the voltage on the DTR line drops below 4.0 volts the Actisys adaptor resets and communication with the Logger stops.
Solution: Try using a USB to Serial converter instead of a laptop mounted serial port but see also the paragraph above.
Problem: Unreliable or faulty drivers for the USB to Serial converter.
Explanation: The drivers shipped on the CD-rom with USB to serial converters are often several years old as the converter may have been in stock for some time and the manufacturers often do not create a new CD-rom whenever the drivers are updated.
Solution: Obtain the latest drivers for the converter. Bear in mind that any brand name on the converter may not be the manufacturer and the manufacturer may not have written the drivers.
To check which drivers are present:
Go to MY COMPUTER - CONTROL
PANEL - SYSTEM - HARDWARE - DEVICE MANAGER.
Click on ports then select the
USB serial port, right click on it and select PROPERTIES.
The manufacturer
is normally listed on the General page and the driver provider, date and version
is on the driver page.
Further information: Most USB to serial converters use either:
a
Prolific device (drivers are here http://www.prolific.com.tw/eng/download.asp
).
or
a FTDI device (drivers are here http://www.ftdichip.com/Drivers/VCP.htm
).
For converters known to use one of these two devices and drivers see APPNOTE: Using a USB to Serial converter with a Ranger Logger in the Pronto Knowledge base. Note however that we have not tested all of these converters to ensure hardware compatibility with the Actisys IR220L+.
Problem: When PmScreen is started the COM port and baud rate in use may not match that of the connected instrument.
Explanation: The port and baud rate used when PmScreen attempts to
connect is determined by the method used to launch it.
If PmScreen is launched
from within Pronto for Windows by clicking on the PmScreen button on the Logger
Bar the port and baud rate used is that from the Logger Address selected in
the adjacent drop down list.
If PmScreen is launched from the TOOLS menu within Pronto or directly using an icon on the desktop or the ALL-PROGRAMS menu, then the port and baud rate selected are those last used.
For example, if a PM2000 is connected through the infra-red adaptor to COM1 and PmScreen is launched then it may try and connect to a PM7000 on COM6 at 921600 if this is what was last used. In this case communication will fail.
Solution: Launch PmScreen through Pronto for Windows after selecting the Logger to which you wish to connect in the Logger Bar, or alternatively edit the icon on your desktop (or the item in your start menu) to include command line parameters so PmScreen connects to a specific port as shown below:
Problem: PmScreen appears to hang while attempting to connect in the presence of certain types of Fluorescent lights.
Explanation: Compact Fluorescent lights with electronic ballasts turn
on and off at a few kHertz. This rapidly varying light level is seen by the
Actisys infrared adaptor as noise.
Tests done by us indicate that the
range over which interference occurs was 3 to 4 meters (10 to 12 feet)
during the warm-up period for the lamp. Once warmed up the range of interference
dropped to about a meter (3 to 4 feet).
The interference produced by the
lamp is interpreted by PmScreen as being a response from multiple Loggers
at the same time and it takes PmScreen a couple of minutes to decide that it
is noise and display an error.
Solution: Do not use the Infrared adaptor within range of compact fluorescent lamps.
Problem: Operational Range is reduced in bright filament lighting or direct sunlight.
Explanation: The Actisys IR220L+ Infrared adapter is tolerant of external
light interference. Direct sunlight or very bright filament bulbs do however
reduce the operational range.
The table below shows the effect on the range
using a 60 Watt filament bulb near the Infrared Adaptor during communications
with a PM2000.
Illumination Operational
Range.
none 1.75
meters
60 Watt at 1 meter 1.10 meters
60
Watt at 0.5 meter 0.63 meters
60 Watt at 0.2 meter 0.41
meters
60 Watt at 0.1 meter 0.39 meters (this is about the
same as direct bright sunlight on a clear day).
60 Watt at 0.05 meter 0.33
meters
Solution: Position the Infrared adaptor within 0.3 meters (12 inches) of the receiver in the Logger in bright light conditions.
Problem: The PM1000 and PM2000 do not respond to external communications when the timekeeper button cell battery is exhausted.
Explanation: When the timekeeper battery is exhausted the real time clock runs at the wrong speed (often two or three times as fast as it should).
The PM1000 or PM2000 use the real time clock to detect a legitimate "Wakeup" sequence by counting the number of data bits that arrive during a fixed period. If the real time clock is running too fast then the number of data bits is not within tolerance and a legitimate Wakeup is treated as noise and ignored.
A PM2000 that is left on the shelf off charge will drain the main batteries in a few weeks after which the real time clock will run off the button cell for a further 3 to 5 years. If the Logger is used or charged at least once every few weeks then the button cell will run down much slower.
Solution: Dismantle the Logger and change the CR1616 button cell.
APPNOTE: Using a USB to Serial converter with a Ranger Logger
APPNOTE: Checklist for Logger communication problems
APPNOTE: Recommended baud rates for different Loggers
Last reviewed: May 01, 2008
© 2008 Outram Research Ltd. All rights reserved.