(((MiWSN)))
Mi Wireless Sensor Network
Self-Monitoring Wireless Sensor Network Solutions

Technical Notes

 

Technical Note - Sensor Battery Life
The Mi-Sensor-1 uses a user replaceable CR2032 lithium battery. There are several factors that affect the battery life of the sensor. A new battery is expected to have a power capacity of 240mAh at 21 degrees Celsius down to 2.0 volts. Lower average temperatures will produce less usable battery life. If the sensor has motion sensing enabled its battery life will be reduced by approximately 20%. If periodic transmission rates are enable and changed from 1 hour to 1 minute, battery life will be reduced by approximately 20%. Another factor that will reduce battery life is the transmission of a large number of alarms. For each 100 alarms per day battery life will be reduced by approximately 1%. The low battery warning will be sent when battery voltage reaches 2.1 volts and this indicates there is approximately 2% battery capacity remaining. The battery should be changed shortly there after.

 

Technical Note - Temperature Response
The Mi-Sensor-1 uses an internal temperature sensor that has a response time of approximately 30 degrees Celsius per minute air to case. The temperature sensor is mounted within an ABS case that dampens the thermal response time of the sensor to approximately 3 degrees Celsius per minute. This does not make the Mi-Sensor-1 suitable for monitoring temperatures that change very quickly. This sensor is suitable for monitoring room and outdoor temperatures as they typically change slowly.

 

Technical Note - Moisture / Contact Port
The Mi-Sensor-1 uses a capacitive sensing port to detect the presence of moisture, wire ends shorted, or wire ends open. It the sensing wire is too long it can lead to a false reading of moisture present or contact shorted. The moisture condition or contact closure must exist for greater than one second for the sensor to detect the condition.

 

Technical Note - RF Range
There are many environmental factors that affect RF range. The objects between and near the sensor and gateway affect range. Metal objects will reduce range dramatically. For maximum range try and minimize objects near or between the sensor and gateway. The sensor and gateway antennas are somewhat directional and their orientation will affect range. Also moving the sensor and gateway a few centimeters in any direction can affect range. The gateway records the signal strength of the messages received from the sensors in dBm units. The more negative the dBm value, the weaker the signal. For free space transmissions, a reduction of 6 dB is equal to doubling the distance. This is useful in determining how far you can place the sensor from the gateway. Additional gateways may be configured as repeaters to extend the range of sensors from the gateway connected to the local area network.

 

Technical Note - Email Servers
The gateway will communicate with email servers that support SSL 3.0 encryption or no encryption. The gateway does not support email servers using TLS encryption. The gateway also supports password authentication or no password authentication. A partial list of email servers that the gateway has successfully been tested is as follows:

Host SMTP Server SMTP Port Use SSL Authentication Working
Sendinblue smtp-relay.sendinblue.com 2525 No Yes Yes
SMTP2GO mail.smtp2go.com 2525 No Yes Yes
mailgun.com No Yes Yes
mailrelay.com No Yes Yes
mailjet.com No Yes Yes
mailerlite.com No Yes Yes
SendGrid smtp.sendgrid.net 25 No Yes Yes
MAIL smtp.mail.com 587 No Yes Yes
GMX mail.gmx.com 587 No Yes No, added TLS
Gmail smtp.gmail.com 465 Yes Yes No, stopped supporting SSLv3
Yahoo smtp.mail.yahoo.ca 465 Yes Yes No, stopped supporting SSLv3

 

Technical Note - IP Network
There must be a unique Host Name, MAC Address, and IP Address configuration parameters in place in order for IP communications with the gateway to operate correctly. After resetting the gateway to default parameters, it will require a Local Area Network DHCP server to assign an IP address to the gateway. Once the gateway is accessed using the assigned DHCP IP address, it may be changed to a static address if required by your network. If multiple Mi-Gateway-1 gateways are used in your network, ensure that the MAC Address is unique for each one.

 

Technical Note - Wireless Network
The WiWSN products operate on a choice of 16 RF channels. The sensors send very small redundant radio packets to the gateway allowing the products to operate reliably on already crowded channels. If interference from other equipment is experienced, the sensor and gateway can be set to another channel. Multiple sensor/gateway networks may operate on the same channel independently if they use a different RF Key. The gateway will throw away sensor messages that do not have the correct RF Key. It is possible to use multiple gateways to receive the same sensor message as long as the RF Channel and RF Key are the same. This will expand the network coverage. The channel to frequency in MHz is as follows:

Channel MHz Channel MHz
0 2405 8 2445
1 2410 9 2450
2 2415 10 2455
3 2420 11 2460
4 2425 12 2465
5 2430 13 2470
6 2435 14 2475
7 2440 15 2480

 

Technical Note - Network Capacity
The Mi Wireless Sensor Network will handle an unlimited number of sensors connected to the gateway. The gateway status page will only display the last 10 different sensor messages received within the network. When a sensor message is received it is queued by the gateway for transmission to the SMTP server. The gateway can only send one message at a time to the SMTP server. Depending on the type of SMTP server and the settings it can take anywhere from ¼ of a second to several seconds to send an email message. This will limit the number of messages that can be sent when multiple sensors are all sending notifications at the same time.

 

Technical Note - SSL Keys
The Mi-Gateway supports SSL keys up to 2048 bits which is sufficient for most public SMTP servers. If you experience problems connecting to your SMTP server check the minimum key length supported. Error 32769 may indicate your smtp server does not support SSLv3.

 

Technical Note - SMTP Error Codes
The following error codes are returned by the Mi-Gateway when sending emails.
Code     Meaning

32768    The SMTP server could not be resolved
32769    The connection to the SMTP server failed or was prematurely terminated
32770    Server time out
200    (nonstandard success response, see rfc876)
211    System status, or system help reply
214    Help message
220    Service ready
221    Service closing transmission channel
250    Requested mail action okay, completed
251    User not local; will forward to <forward-path>
354    Start mail input; end with <CRLF>.<CRLF>
421    Service not available, closing transmission channel
450    Requested mail action not taken: mailbox unavailable
451    Requested action aborted: local error in processing
452    Requested action not taken: insufficient system storage
500    Syntax error, command unrecognized
501    Syntax error in parameters or arguments
502    Command not implemented
503    Bad sequence of commands
504    Command parameter not implemented
521    Domain does not accept mail (see rfc1846)
530    Access denied
535    SMTP Authentication unsuccessful/Bad username or password
550    Requested action not taken: mailbox unavailable
551    User not local; please try <forward-path>
552    Requested mail action aborted: exceeded storage allocation
553    Requested action not taken: mailbox name not allowed
554    Transaction failed

Technical Note - GMAIL Security
 Google has extra security on SMTP use.

IP address location change - Access https://accounts.google.com/displayunlockcaptcha to let Google know your IP address location changed. This may fix error 32769.

Standard SSL authentication - Log into https://accounts.google.com and under Security turn Allow less secure apps ON for standard SSL authentication. This may fix error 534.

Standard SSLv3 - GMAIL has stopped supporting SSLv3. This may be the cause of error 32769.

 

Technical Note - Monitoring Service Login
 You can make a login short cut to the monitoring servce a single tap/click by adding the following URL to your home screen;

http://miwsn.com/Monitor/Login.php?Submit=Login&User=USER&Password=PASSWORD

Where USER and PASSWORD are the ones you created with Create New User.