Frequently Asked
Questions:
Squirrels and Darca
Q. What are Darca's System Requirements?
- PC running Windows 98/ME/NT/2000/XP/Vista
- CDROM drive (for installation)
- 16Mb RAM
- 8Mb free hard disk space for program
- Additional hard disk space for data
- VGA (or better) display
- One unused serial port (or USB slot if used with a USB to Serial Converter)
- Windows compatible modem (if remote connection to Squirrel is desired)
- LC68 cable
- Eltek 1000 Series / RX250AL Squirrel
There are a number of reasons that this problem could occur:
- The Squirrel does not have a power source (either batteries in the
Squirrel’s battery compartment or an external mains power supply
(MP12U).
- The Squirrel is not asleep. To correct this, select OUTPUT mode and
wait 3 seconds for the Squirrel’s display to go blank.
- You are trying to connect to a networking Squirrel but have not selected
the ‘Networked Squirrel’ option in the Settings|Communications
dialog.
If you are using a Modem connection:
- The Modem is not connected to your PC.
- The Modem is not connected to your phone line.
- The Squirrel is not connected to the remote modem by an LC69 cable.
- Your Modem is not installed in Windows properly. Check the ‘Modems’
section of Control Panel.
- The remote Modem has not been configured correctly.
If you are using a Direct connection:
- The Squirrel is not connected to your PC by an LC68 cable.
- The LC68 cable is plugged into the wrong COM port – check your
settings in the Settings|Communications dialog.
- The baud rate is set wrong in the Settings|Communications dialog.
All 1000 series / RX250AL Squirrels manufactured since the year 2000 will
communicate at 38400 baud or slower.
It is very important to correctly configure the modem that is going to
be connected to the Squirrel. Most problems involving Darca and modems
can usually be traced to the Squirrel’s modem not being set up.
Connect the modem directly to the computer using the RS 232 port, which
is usually at the back of your computer and labeled Comm 1 or Comm 2.
To configure this modem you will need to use a simple terminal emulation
program such as Windows Terminal. You can then send AT commands to the
modem in order to configure it in the way you require. When using such
a program, be sure to set it to the correct Comm port, and to the baud
rate which you will be using once the modem is connected to the Squirrel.
Unfortunately, as each manufacturer has their own version of the AT
command set, this help file cannot list the necessary commands for your
particular modem. However, most modern modems have sensible defaults and
clear instruction manuals.
IMPORTANT: These guidelines assume that all the modem’s settings
are the ‘factory defaults’. If this modem is brand new, then
this is probably so. If not, look up how to restore the defaults in the
modem’s handbook. On some modems, some of the settings described
below may require a tiny DIP-switch to be set, rather than an AT command
to be sent. Occasionally, a manufacturer will put more than one ‘factory
default’ profile in the modem. In this case, make sure that the profile
has auto-baud rate negotiation and hardware (not software) flow control.
N.B. references to RTS/CTS mean hardware flow control, which is appropriate.
References to XON/XOFF mean software flow control, which would be unsuitable.
These instructions assume you have a new, high-speed modem with a data
input buffer of at least 1k. Most modern modems conform to this requirement.
- Ensure that the baud rate in the terminal emulator you are using is
set to a baud rate that is compatible with the Squirrel. This is typically
19200 baud.
- Leave the modem’s hardware flow control enabled. The Squirrel
cannot use flow control, but the data packets that it sends are so small
they will fit into the modem’s input buffer without over-filling
it and causing the transmission of flow control signals. The error correction
and data compression can also be left enabled.
- Since Darca will ultimately be dialing this modem up, it needs to
be told to automatically answer any calls. Thankfully, this is always
done with a particular S-register (S0). So, to set the modem to answer
after 2 rings, the following should be sent:
Should you require the modem to answer after 4 rings, substitute the
2 for a 4. Some modems require a DIP-switch to be set to enable auto
answering.
- This new configuration must be saved in the modem so that whenever
the power to the modem is turned on this new profile will be used. It
is important to make sure that the baud rate at which you send the following
command is compatible with your Squirrel (i.e. 19200 baud or slower
for 1000 Series / RX250AL Squirrels), as you are also storing this baud
rate along with the settings that have changed in points 2 & 3.
The exact AT command will depend on your modem, but is typically:
or |
AT&W
AT&W1 |
[Enter].
[Enter]. |
A. Make sure the communication baud rate is set to 9600 in Darca. At
other speeds the logger may not 'wake up' reliably.
Q. I have problems with connection reliability when using Darca with
an instrument attached to a GSM modem.
A. Due to the nature of GSM you are more likely to get checksum errors
on data from and to the logger. To prevent Darca from 'giving up' the
connection, with an error like 'the logger could not be woken' you can
increase the numbers of times Darca retries to 'wake up' the logger and
the number of times it will retry a command to the logger. To do this
go to settings then preferences and select the timing tab. Increase the
wake up retries to 25 and the command retries to 10. This is particularly
important if the logger is also scanning or logging the inputs very frequently.
- Clear the memory while logging is in progress
- Start logging when the memory is full
- Start logging if no channels have been selected
- Perform multiple runs if memory is in continuous mode
- Reset pulse count while logging is in progress
- Change date and time while logging
- Change start date and time while logging
- Change log and sample intervals while logging
It is not possible to change the following either when there are readings
stored in memory or when logging is in progress:
- Log mode
- External trigger mode
- Memory mode
- Channel set up and ranges
- Engineering unit ranges
- Memory size
- Language type
- Sensor switch on time
- Date format
- Filter frequency
A. Microsoft decided not to include the windows help system with Windows
Vista by default. Darca plus and Darca Lite currently use this form of
help. You can install the help system via microsoft from the following
location:
http://www.microsoft.com/downloads/details.aspx?familyid=6EBCFAD9-D3F5-4365-8070-334CD175D4BB&displaylang=en
A bug can cause this problem if you attempt to set a local alarm on a transmitter
that does not have the alarm hardware option. To cure the problem, use Tx setup
to ensure all Hi and Lo alarms are set to 'Not Set'.
Q. What is the best way to contact a logger remotely
using GSM?
At the logger:
For the logger specify the GSMSQ kit, this comprises a Wavecom Xtend modem,
antenna and lead to connect the modem to the logger. A SIM is not included.
Note that the Modem is powered via this lead getting its power from the MP12U
(external power supply) connected to the logger. This means it is essential
an MP12U be specified if the modem is to be connected to a Squirrel conventional(wired)
logger.
The Wavecom Xtend is preconfigured for the application. Following the User Instructions
provided with the kit will get you going quickly but you must have a valid SIM
to hand.
If the remote PC uses a landline modem to connect to the GSM network then the
SIM for the GSMSQ must be equipped with an analog data number. This is the dial
up number that will be used in Darca at the PC. A so called analog data number
is a requirement of the GSM network and remote GSM unit (the GSMSQ) to identify
itself as a data device only. Applying for the analog data number can be difficult
/extremely difficult to get from your network provider. The analog data number
is linked to the voice number/barcode of the SIM you have acquired.
Benefit of using a GSMPC at the PC end:
If the remote PC is quipped with a dedicated GSM modem such as the GSMPC kit
from Eltek, then the remote, logger GSM and PC GSM are communicating directly.
This avoids the need for an analog data number altogether.
Communications between the PC and logger is more reliable if a GSM PC is installed
at the PC end.
The GSMPC kit consists of a Wavecom Xtend modem, antenna, modem to PC serial
lead and AC to 12V DC power supply. A SIM is not included. Following the User
Instructions provided with the kit will quickly get you going.
The SIM can be a low cost contract SIM as data is via the voice channel of the
GSM network.
If you have an FAQ that you would like share with others in this section then
please contact us at sales@eltekdataloggers.co.uk.
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