CMG-DCM
Data Communications Module
Operator’s guide
Part No. MAN-DCM-0001
Designed and manufactured by
Güralp Systems Limited
3 Midas House, Calleva Park
Aldermaston RG7 8EA
England
Proprietary Notice: The information in this manual is
proprietary to Güralp Systems Limited and may not be copied
or distributed outside the approved recipient's organisation
without the approval of Güralp Systems Limited. Güralp
Systems Limited shall not be liable for technical or editorial
errors or omissions made herein, nor for incidental or
consequential damages resulting from the furnishing,
performance, or usage of this material.
Issue B 2005-12-22
CMG-DCM
Table of Contents
1 Introduction............................................................................................................................5
1.1 Inside the DCM................................................................................................................7
Serial port services.............................................................................................................8
Network services...............................................................................................................8
2 Installing the CMG-DCM....................................................................................................10
2.1 Overview........................................................................................................................10
2.2 Power supply..................................................................................................................10
2.3 Connecting to a single computer....................................................................................11
Connecting over a serial link...........................................................................................11
Connecting over Ethernet................................................................................................12
Using an internal modem.................................................................................................13
Connecting over USB......................................................................................................13
2.4 Connecting to a local network........................................................................................14
Wi-Fi................................................................................................................................16
Connecting to the Internet................................................................................................16
2.5 Connecting digitizers and external hardware.................................................................17
2.6 Setting up the CMG-DCM.............................................................................................17
Web setup........................................................................................................................18
3 Usage.....................................................................................................................................21
3.1 General notes..................................................................................................................21
3.2 The DCM as a data store................................................................................................21
3.3 The DCM as a GCF data source.....................................................................................25
Accessing the DCM command line through gcf_out.......................................................26
Sensor arrays....................................................................................................................27
3.4 The DCM as a network data hub....................................................................................28
Communicating with digitizers.......................................................................................29
Data storage and retrieval................................................................................................31
Real-time data transmission.............................................................................................33
3.5 Troubleshooting DCM installations...............................................................................35
I cannot connect to the DCM's DATA OUT port using a terminal program...................35
I cannot see the DCM's Web site over HTTP or HTTPS................................................36
I cannot connect to the DCM's Scream! server................................................................36
I cannot GCFPING the DCM's Scream! server...............................................................36
I can GCFPING the DCM's Scream! server, but no data appears...................................37
The DCM is not receiving any data streams....................................................................37
The DCM is receiving streams, but they do not contain any data...................................38
The DCM receives streams, but gaps appear in the data some minutes after boot-up....39
The DCM receives streams, but 2-minute gaps appear in the data at 4-hour intervals.. .39
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4 Configuration options..........................................................................................................40
4.1 General...........................................................................................................................40
4.2 Disk................................................................................................................................41
4.3 Serial port configuration.................................................................................................43
4.4 Network configuration....................................................................................................46
Ethernet port....................................................................................................................46
Static routes.....................................................................................................................47
DNS setup........................................................................................................................48
Incoming mail setup........................................................................................................49
Outgoing mail setup.........................................................................................................50
Remote access..................................................................................................................51
Administrators.................................................................................................................52
PPP...................................................................................................................................53
mgetty..............................................................................................................................54
4.5 Data transfer...................................................................................................................55
Scream!............................................................................................................................55
Scream! Client.................................................................................................................56
AutoDRM........................................................................................................................56
HTTP server.....................................................................................................................57
HTTP client.....................................................................................................................57
CD1.0...............................................................................................................................57
CD1.1...............................................................................................................................58
DSS..................................................................................................................................60
SEED...............................................................................................................................62
5 Actions...................................................................................................................................65
5.1 Data Viewer....................................................................................................................65
The icon bar.....................................................................................................................66
The stream list.................................................................................................................66
5.2 Digitizer Setup................................................................................................................67
General digitizer settings.................................................................................................68
Digitizer output control...................................................................................................69
Trigger criteria.................................................................................................................71
Auxiliary (“Mux”) channels............................................................................................74
Sensor mass control.........................................................................................................75
5.3 Disk tools........................................................................................................................76
Partition, and format disk................................................................................................76
Check disk filesystem......................................................................................................76
Flush flash........................................................................................................................76
5.4 Disk files.........................................................................................................................77
5.5 Camera............................................................................................................................77
5.6 Recent Log Entries.........................................................................................................77
5.7 Summary.........................................................................................................................78
Network configuration ....................................................................................................78
DNS configuration ..........................................................................................................79
Data Out Port, Serial Port A, Serial Port B......................................................................79
Flash Status......................................................................................................................80
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Tamper lines....................................................................................................................80
Disk Status ......................................................................................................................80
Software Versions............................................................................................................81
6 Inside the DCM....................................................................................................................82
6.1 File systems....................................................................................................................83
6.2 Command line tools.......................................................................................................85
6.3 Configuration..................................................................................................................86
Digitizer console access...................................................................................................87
6.4 Monitoring......................................................................................................................88
Data flow.........................................................................................................................88
Digitizer status.................................................................................................................89
Tamper lines....................................................................................................................90
6.5 Updating the DCM.........................................................................................................91
Over the Internet..............................................................................................................91
From the hard disk...........................................................................................................91
Removing support packages............................................................................................91
The firmware...................................................................................................................92
Appendix A Connector pinouts.............................................................................................94
Appendix A.1 Modular DCM units......................................................................................94
PORT A and B.................................................................................................................94
DATA OUT port..............................................................................................................94
USB connector.................................................................................................................95
NETWORK connector.....................................................................................................95
Appendix A.2 Integrated DCM units...................................................................................96
DM/AM module output...................................................................................................96
Appendix B Sensor and digitizer types.................................................................................97
Appendix B.1 Sensor response codes...................................................................................97
Appendix B.2 Digitizer type codes......................................................................................98
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Operator's guide
1 Introduction
The CMG-DCM is a versatile Linux-based module for storing and transmitting
data captured using Güralp Systems Limited's range of seismic measuring
equipment. Data can be gathered from up to three digitizers compatible with the
Güralp Compressed Format (such as the Güralp CMG-DM24), and stored in its
on-board Flash memory, from where it is written from time to time to a USB
hard disk or to another device on your network. Once data is on the hard disk,
you can connect to the DCM by various means to retrieve it.
Depending on your site requirements, the DCM may be supplied in several
formats. Although these look different, they all share the same internal features.
• A stand-alone DCM, housed in a high-impact copolymer polypropylene
case, may be connected to a digitizer through mil-spec connector cables
and installed in a ground station or other location remote from the
digitizer and seismometer. The stand-alone DCM can accept data from
up to three devices connected to it through RS232 ports.
Stand-alone DCM units are normally supplied with high-capacity
removable USB/FireWire disks for data storage. These disks allow the
DCM to be used as part of completely autonomous installation in cases
where communications links are poor or non-existent.
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Retrieving data from a DCM's disk can be done by plugging it into a
computer compatible with the USB or FireWire mass storage standards.
Disks can be swapped at any time with no risk to data.
• A stand-alone DCM can also be supplied in a form factor suitable for
mounting in a standard 19” rack. Such a DCM will normally come
equipped with eight additional serial ports TTS0-7, and an optional State
of Health (SOH) interface for monitoring or tamper evidencing.
Up to four modules may be mounted side-by-side in a 19” rack.
• An integrated or modular DCM may be combined with a digitizer and
seismometer to produce a single unit capable of measuring seismic data,
storing, and passing it on over a network:
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This form of DCM uses an integrated 26-pin connector to communicate,
rather than having separate ports.
A DCM in any of these forms may be supplied in the configuration most
suitable to your requirements, depending on how you wish it to be connected to
your network, and how its USB interface is to be used. The two sets of options
are independent.
• Using the 10BaseT Ethernet network option, you can connect the DCM
to any TCP/IP network.
• Alternatively, an internal PCMCIA modem may be supplied, through
which you can use a dial-up or other communications link to connect to
your home network. Most 56k analogue and ISDN-type modems are
supported.
• As a third option, an 802.11b Wi-Fi module may be installed.
• If the USB client option is installed, you can connect the DCM's USB
port to a computer and communicate with it as if it were on a private
network.
• If the USB host option is installed, you can connect the USB port to an
additional peripheral, such as a camera or external hard disk.
Whichever set of options you choose, you can use any free RS232 port to
connect the DCM to a single computer for local monitoring and configuration,
or through it to a wider network using PPP/SLIP.
1.1 Inside the DCM
The DCM's configuration is maintained by an internal database. All of the
flexibility of the unit is provided through this configuration database. Before
you deploy the DCM, you will need to configure it for your needs, either using
its on-board Web server or over a direct serial link.
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The two main areas which need to be configured determine the different
services which the DCM provides from its serial and network ports.
Serial port services
You can use either the DCM's console or its Web configuration interface to
configure the serial data ports. The serial.x.service configuration option
determines which service each port provides.
• The simplest service is getty. This creates a console port, which you can
use to log in to the Linux operating system of the DCM directly.
• The mgetty-r service is similar, but is more suited for serial links
including modems, in which the link is not always active. This is the
default option.
• Any of the serial ports on the DCM can be directed to transmit GCF
(Güralp Compressed Format) data by setting the serial.x.service option
for that port to gcf_out. You can then run Scream! or other software on
your computer to receive the data. You will not be able to access the
Web configuration interface using this service, although you may be able
to configure attached digitizers from Scream!.
• Likewise, any serial port can be set to listen for incoming data (e.g. from
a connected digitizer or another DCM) by setting the serial.x.service
option to gcf_in. The DCM will automatically combine this data with
any other streams it is receiving, and send it on using all gcf_out ports
and any other transmission methods which have been configured.
• You can log in to the Linux operating system over a modem link by
setting the serial.x.service option to mgetty. mgetty listens for incoming
calls from your computer and sets up a login session for you. You may
need to configure minicom or hypertrm to communicate with your
own modem before you can do this.
• Both mgetty and mgetty-r can recognize incoming PPP connections and
will automatically run a PPP daemon if you attempt to connect to the
DCM in this way.
Network services
Because the DCM is a fully-fledged Linux machine, you will need to set up
networking before you can use it. Advanced networking is beyond the scope of
this manual. For a basic setup, you will need to perform the following actions:
1. Assign the DCM an IP address. By default, the DCM will try and use
DHCP (Dynamic Host Configuration Protocol) to find its own IP
address. However, this requires a DHCP server on your network. If you
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do not have a DHCP server, you will have to set the IP address yourself.
2. Find out the IP address the DCM is using (if you have not set it
yourself).
3. If necessary, configure your own computer's IP address so that it can
communicate with the DCM.
See Section 2.4, “Connecting to a local network” for full details.
Once you have connected the DCM to your local network or to the Internet, you
can use a wide range of methods to retrieve data from it.
• All DCM units feature an on-board Web server, which allows you to
monitor and configure the station from any browser (and download data
by HTTP, if enabled.)
• For maintenance, you can log in to the operating system directly over the
secure shell protocol, SSH, and use all the standard Unix/Linux tools.
• A GCF server can be set up to transmit data to any application that
supports the GCF format (such as Scream!, Antelope, or Earthworm.)
• The DCM can act as a CD1.0 or CD1.1 transmitter to a specified client,
or to multiple clients as an option.
• Optionally, the DCM can also receive and process AutoDRM messages.
In addition, the DCM can be configured to act as a data client, receiving GCF
and CD1.0/1.1 data streams, combining these streams and storing or
retransmitting them as appropriate. See Chapter 3, “Usage” for full details.
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2 Installing the CMG-DCM
2.1 Overview
The DCM is effectively a low-power Linux computer dedicated to seismic data
flow tasks. Resources permitting, the DCM can perform any computational task
you require. Because of this flexibility, the DCM must be configured for your
particular purposes before it can be used:
1. If you only need to use the DCM as a data store, you can gain console
access over the serial port for configuration.
2. If you are going to use the DCM as part of a TCP/IP network, you must
set up its IP address and other networking parameters before you can
connect to it. Whilst the network is inoperative, you will need to connect
to the DCM console over a direct serial connection. We recommend that
you configure the DCM correctly, to the best of your knowledge, before
shipping it into the field.
3. If you want to connect to the DCM using TCP/IP over modem links, you
must set up PPP over these links. Configuring PPP is beyond the scope
of this manual: please see the Linux man page for ppp for details, or the
Linux PPP HOWTO.
4. Once communication with the DCM is working, you should set up the
serial ports on the DCM to provide the services you require.
5. When all ports are configured, you can use the DCM to set up attached
Güralp digitizers and digital instruments.
2.2 Power supply
The stand-alone DCM receives its power from lines in its data connectors. All
three of these ports are Güralp standard 10-pin combined serial/power
interfaces. Cables are available from Güralp Systems which enable you to
connect a 9-pin D serial interface and 2-way power connector to any of these
ports.
You can power the DCM from whichever data port is most convenient, whether
or not it is being used for receiving or transmitting data. However, you should
always supply power to the DATA OUT plug if possible, since it is easy to
accidentally short the pins of a male connector. Attached digitizers and sensors
are powered from the same supply as the DCM. Any 12 V DC power supply
may be used; if using batteries, we recommend that you use a unit with lowvoltage disconnect to avoid excessive drain.
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A rack-mounted DCM has a separate POWER IN connector on the back panel,
which should be attached to a 12 V DC supply. There is also a POWER OUT
connector on this panel, which allows you to daisy-chain several DCM units
together. The POWER OUT connector is provided merely for convenience: lines
from the POWER IN connector pass straight through.
An integrated DCM receives its 12 V DC power from two pins in its single
connector. See Appendix A, “Connector pinouts” for the positions of these pins.
2.3 Connecting to a single computer
In autonomous or temporary installations, you will only need to connect the
DCM to one computer (e.g. a laptop) for initial configuration. Follow these
instructions to make the DCM communicate with your computer.
Note that your computer must either have an RS232 (serial) port for initial
connection, or be running its own DHCP server. DHCP servers are available for
Windows, but are not supplied as standard.
If you want to connect the DCM to a local area network, follow the instructions
in Section 2.4, “Connecting to a local network” instead.
Connecting over a serial link
The DATA OUT port can be used to connect a DCM to a single computer
through a direct serial link. This link can be used to log in to the Linux
operating system of the DCM and transfer files. It is most useful for
maintenance and troubleshooting over a low-bandwidth connection, and for
initial setup.
To communicate over a serial link:
1. Connect an RS232 reverse serial cable between the DCM and your
computer. A suitable cable should have been supplied with the unit.
2. Run a terminal emulation program on the computer. The built-in
programs minicom for Linux, and hypertrm for Microsoft
Windows, can be used for this.
3. Configure the baud rate of the serial link. By default, the DCM uses a
baud rate of 115200, with 8 data bits, no parity bit, and one stop bit, and
without flow control.
4. Log in with your username and password, or root if you have not yet
created one. See http://www.faqs.org/docs/Linux-
HOWTO/Text-Terminal-HOWTO.html for full information on
how to set up terminal emulation under Linux.
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5. You now have access to the DCM's console and all of its functions. You
should change your password, if you have not done so already, with the
command passwd
For full details on how you can configure the serial ports of the DCM, see
Section 4.3, “Serial port configuration”.
Connecting over Ethernet
You can use a “crossover” Ethernet cable to connect the DCM directly to your
computer. This has the same effect as connecting the DCM and your computer
to a separate hub using standard Ethernet cables: the two machines will
consitute a network segment, and each will have its own IP address on that
segment. See Section 2.4, “Connecting to a local network” for details on how to
configure TCP/IP on the DCM.
If your computer has two network interfaces, and one is connected to a local
area network, you may be able to set up a network bridge between the DCM's
segment and the rest of the network. For example, if you are using Microsoft
Windows XP:
1. Connect to the DCM's console over a serial link.
2. Because you are connecting the DCM to a single computer, you will
probably not be able to use DHCP. You should configure the DCM to
disable DHCP and use an IP address in a private range such as
192.168.0.x:
gcfgdbset net.eth.0 static
gcfgdbset net.eth.0.address 192.168.0.2
gcfgdbset net.eth.0.netmask 255.255.255.0
Here, 192.168.0.2 should be replaced with the IP address you want
the DCM to use.
Allow a short time for the DCM to reconfigure the network.
3. On your computer, select Start Control Panel Network→ →
Connections. Right-click on the interface connected to the DCM, and
select Properties.
4. Click on Internet Protocol (TCP/IP), then Properties.
5. Select Use the following IP address, and fill in an address on the same
subnet as the DCM (e.g. 192.168.0.49). Click OK, then OK in the
Connection Properties window.
6. Check that you can connect to the DCM using its new IP address by
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Operator's guide
opening its Web site at
http://192.168.0.2/
7. Advanced usage: If you later want to connect your computer to a local
area network, you can make the DCM visible to that network by setting
up a network bridge. Before doing this, you must make sure that the IP
addresses you have chosen for the DCM and your computer are suitable
for the local network you want to connect it to.
To set up the bridge, open the Network Connections window, and select
the connections corresponding to the DCM and your network. Click
Bridge connections, and follow the instructions in the wizard.
If you are using Linux or another operating system, you should see its own
documentation for more details.
Using an internal modem
If you have ordered a DCM with an internal PCMCIA modem, it will
automatically listen for incoming PPP connections. This is most useful if the
DCM is integrated into a borehole instrument, which can then be connected to a
modem at a central data collection point. The modem within the DCM appears
on the Web configuration interface as a serial port, allowing you to change the
service it provides and the data transfer settings it uses. For example, if you do
not want the internal modem to use PPP, you can configure it to use mgetty
instead and log in directly.
Connecting over USB
If your DCM is equipped with the USB client interface, you can connect it
directly to any computer with a USB socket. When this is done, the computer
treats the module as if it were a standard network card. For example, to connect
the DCM to a PC running Microsoft Windows, you should:
1. Link the DCM's USB port to any available USB socket on the computer.
2. After a short wait, Windows should report that a new USB device has
been detected. When prompted to install drivers for it, you should use
the ones provided on CD by Güralp Systems.
Once the “network card” is installed, the two machines will consitute a network
segment, and each will have its own IP address on that segment. See Section
2.4, “Connecting to a local network” for details on how to configure TCP/IP on
the DCM. If you wish, you can set up a network bridge between this connection
and a local area network or the Internet as described above.
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2.4 Connecting to a local network
The DCM is normally supplied with a 10BaseT Ethernet port. This port can be
used to connect to your local network.
When the DCM starts up, it will try to find a DHCP server on your network to
assign it an IP address.
If you use DHCP on your network, and you want to access the DCM's Web
server or console over the network, you may be able to find out from the DHCP
server which address it has given the DCM, in which case you can access it
directly. Otherwise, you will need to connect to the DCM over a serial link to
find out its IP address.
If you do not use DHCP on your network, you will have to set the DCM to use a
static IP address.
1. Make a temporary serial connection to the DCM from a local PC. You
should see the message
DCM login:
2. Enter root and the administrator password. If you have not been given
a password, the default setting is rootme. The DCM will reply with a
prompt:
[root@DCM ~]#
This verifies that the unit is working properly. You should change the
password as soon as you can with the command passwd
3. Connect the DCM's NETWORK port to your network, and power cycle
it. Log in again.
4. If your network does not use DHCP, type
gcfgdbset net.eth.0 static
to make the DCM use a static IP address instead, and set the address
with
gcfgdbset net.eth.0.netmask 255.255.255.0
gcfgdbset net.eth.0.address your-address
Here, your-address should be replaced with the IP address you want
the DCM to use. The IP address you choose must be unique on your
network.
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If you are connecting the DCM to a machine on the same network, you
do not need to configure any more options at this stage.
If your network uses DHCP, you will not need to perform this step.
Instead, ensure the DCM is also using DHCP with
gcfgdbset net.eth.0 dhcp/bootp
5. Issue the command ifconfig
The DCM will reply with technical information on its current network
setup. Each interface is listed separately. The NETWORK port uses the
interface eth0:
eth0 Link encap:Ethernet HWaddr 08:00:20:C0:FF:E2
inet addr:192.168.48.187 Bcast:192.168.48.255
Mask:255.255.255.0
UP BROADCAST NOTRAILERS RUNNING MULTICAST
MTU:1500 Metric:1
RX packets:88045 errors:36 dropped:0 overruns:36
frame:0
TX packets:16308 errors:0 dropped:0 overruns:0
carrier:0
collisions:149 txqueuelen:100
RX bytes:12358214 (11.7 MiB) TX bytes:0 (0.0 B)
Interrupt:76
If the interface is correctly set up, its IP address will be shown after
inet addr: (here, 192.168.48.187.)
6. If you are connecting the DCM to a single computer which does not run
a DHCP server, you will need to configure that computer to use an IP
address on the same subnet as the DCM before they will be able to reach
each other (see “Connecting over Ethernet” in Section 2.3.)
You should now be able to connect to the DCM's Web setup interface by typing
its IP address into any browser, e.g.
https://192.168.0.2/
Scream! and similar software applications should also be configured to use this
address to communicate with the module, if they are intended to communicate
over the network.
Alternatively, you can continue using the gcfgdbset command to set other
configuration options by name. In Chapter 4, “Configuration options”, each
option's name is given in italics. The command syntax to use is
gcfgdbset option-name new-value
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The options will take effect immediately whenever possible. Some changes may
take some time to complete, since services may need to be restarted. The
gcfgdbset command performs only simple checks on the new value, so you
should check the syntax of the option carefully.
Wi-Fi
Optionally, a DCM may be supplied with 802.11 (“Wi-Fi”) hardware in place of
Ethernet. There are two modes in which an 802.11 network may operate:
• In ad hoc mode, data packets are sent out over the wireless connection
indiscriminately and are received by all machines on the network. This is
the simplest style of Wi-Fi network, but consumes more power and
cannot easily be extended to large networks.
• In infrastructure mode, dedicated 802.11 hubs collect data packets,
collate, and distribute them efficiently around the network. These hubs
may also act as transparent extensions to existing (wired) TCP/IP
networks.
The DCM is capable of running in either situation, depending on your
requirements. As far as the computers on the network are concerned, there is no
difference between a TCP/IP network running over Ethernet and one using
802.11 connections, or a mixture of the two.
Once the 802.11 system is running, you will need to run a DHCP service on
your network, or manually set the IP address of the DCM as above.
Connecting to the Internet
If the local network is already connected to the Internet through some other
means (perhaps through a gateway machine), you can create a default route with
gcfgdbset net.eth.0.gateway network-gateway
where network-gateway should be replaced with the IP address of the
gateway on your local network.
The DCM can perform more complex routeing if required. See “Static routes”
in Section 4.4 for more details.
As supplied, the DCM module will accept requests to its on-board Web server
and logins over SSH. In addition, the DCM can be requested by Scream! or
other GCF-compatible software to send GCF streams to your computer.
If the instrument is located on a private network, you may be able to connect to
it from the wider Internet by using a feature implemented by SSH known as
tunnelling. You can use this technique to connect to the DCM through a chain
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of intermediate machines which support SSH. Once this chain is set up, you can
treat the connection as if it were a direct link between the DCM and your
computer. Many standard Internet protocols may be fed through SSH in this
manner. Whether this is possible will depend on the precise configuration of
your local area network. For more details, please see the documentation for SSH
clients such as ssh and putty.
2.5 Connecting digitizers and external hardware
The DCM is designed for use with Güralp Systems digitizers, which
communicate over RS232 or RS422 serial links using the GCF protocol. There
are three RS232 ports available on a stand-alone DCM and ten on a rackmounted model, whilst on a DCM bonded to a digitizer unit only the DATA
OUT port is available (the digitizer is connected directly to the PORT A
interface).
The three serial ports on a stand-alone DCM are labelled DATA OUT, PORT A,
and PORT B. In a typical setup, one or both of the latter two ports are connected
to Güralp DM-24 digitizers, whilst the DATA OUT port connects the DCM to a
computer or serial modem. However, the labels are provided merely for
convenience: internally all three serial ports behave identically. Thus, if the
DCM is connected to a network over Ethernet, you could use all three ports to
communicate with digitizers. Conversely, if you have only one digitizer
attached to a stand-alone DCM, either or both of the remaining two ports could
be used to transmit data gathered by the module.
A rack-mounted DCM has a CONSOLE port with a female connector,
corresponding to the Data out port of the stand-alone model, and nine serial
ports (with male connectors) for communication with digitizers. These appear
on the Web configuration interface with their Linux device names /dev/ttyS0,
S1, etc., up to S7. The TTY port corresponds to /dev/ttySB0, whilst the
CONSOLE port is shown as /dev/ttySA0.
If the DCM has a USB host interface, you can connect it to any USB peripheral
supported by its Linux operating system. For example, you may want to attach a
camera to the DCM, or an additional USB mass storage device. If there is no
hard disk inside the module, it will automatically search for suitable storage on
the USB interface. The DCM may alternatively have been supplied as a USB
client; if this is the case, the USB connection can be used to connect the module
to a single computer (see below).
2.6 Setting up the CMG-DCM
Once a DCM is installed, it must be configured to your particular requirements.
The principal way to set up a DCM is through its on-board Web server, which
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gives you access to all the module's configuration options. You can use this
Web interface over any network connection using the HTTP or HTTPS
protocols. Alternatively, you can log in to the DCM's Linux operating system
and issue commands directly: see Section 6.2, “Command line tools”.
Web setup
The DCM provides a Web interface which you can use to set up the system. To
access this from anywhere on the local network, open any web browser and
navigate to the IP address of the DCM. For example, if the DCM has the
address 10.82.0.1 you would enter
http://10.82.0.1/ or https://10.82.0.1/
https is a secure variant of the http protocol, which ensures that network traffic
cannot be read in transit. The DCM as supplied accepts connections only over
https, although this may be altered if required (see “HTTP server” in Section
4.5)
Your browser may ask you for a username and password to access the Web
configuration interface. An initial root username and password will have been
supplied by Güralp Systems; however, you should check with the DCM's
administrator what username you should use. On a clean install of the Linux
distribution, the password for root is rootme.
Once you have logged in, you will see a Web page similar to this:
The work area on the right displays a summary of the DCM's current state,
including a report on network traffic (produced by the Linux ifconfig
command), details on the services provided by its internal serial ports, and
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current contents of the on-board Flash memory.
The links in the menu on the left lead to various pages where you can change
the configuration of the DCM. Initially, you should be sure to change your
administrator password. Click on Administrators under Network configuration,
fill in the new password in the two text boxes below Existing accounts, near the
bottom of the page, and click Change password. If you want to add any other
named accounts, you may do so at this stage (see “Administrators” in Section
4.4)..
At this point, you should configure the DCM for your own needs. Examples of
how to configure a DCM for several common applications are given in Chapter
3, “Usage”, whilst a full reference is provided in Chapter 4, “Configuration
options”. Some important points to note are:
• The DCM uses internal serial and Ethernet ports to communicate with
the digitizer and the network. Altering the settings under Serial port
configuration or Network configuration may make the DCM
unreachable over the network. You should review carefully any changes
you make to these settings before committing them.
• You can disable the DCM's ssh, http, and https servers using the links
under Data transfer. Before doing this, you should ensure that you will
still have access to the DCM by other means, e.g. by logging in directly
over ssh.
Setting up digitizers
You can change the configuration of attached DM24 digitizers through the
DCM's web page interface. To do this, click on Digitizer Setup beneath Actions
in the menu tree. The DCM will then retrieve the current configuration from the
DM24, which will take a few seconds. This done, a page will appear allowing
you to alter the digitizer's settings:
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A useful feature of Güralp Systems digitizers is the ability to output streams at
several data rates. Each stage of filtering is known as a tap, producing data at a
particular rate. At each tap, incoming data is filtered and its data rate reduced by
a user-selectable factor of 2, 4, 5, 8, or 10 (in the case of Güralp DM24
digitizers). The data rate at each tap must be an integer number of Hz. For a full
listing of the possible tap configurations, see Section 5.2, “Digitizer Setup”.
The initial digitizing process outputs data at a rate of 2000 Hz, which is
decimated at Tap 0 by a fixed factor of 10. You can control which data streams
the digitizer outputs at this point using the top row of the first grid of Z, N, and
E checkboxes on this page. Subsequent grids of checkboxes determine which of
the other taps output data. For example, you could output the Z component at
200 Hz, together with all three components at a lower rate.
You can also set trigger criteria for the digitizer. The criteria can be applied to
any component at any tap, and as soon as they are satisfied, any component with
a checked box in the lower (triggered) row of one of the grids will begin
outputting data in addition to the normal streams. You cannot have the same
component produce both triggered and continuous output at the same tap.
See “Digitizer output control” in Section 5.2 for full details of what you can do.
Using Scream!
If you prefer, you can use Güralp Systems' Scream! software to configure and
calibrate digitizers and sensors through the DCM module, just as if they were
connected directly. For full details on how to use Scream!, please refer to its
own documentation or the extensive on-line help.
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3 Usage
The DCM can be integrated with any system where seismic data needs to be
collected, collated, or converted from one form into another. It is designed to
operate as transparently as possible, and once connected and configured for a
particular role in a system it should not require further maintenance.
The rest of this chapter gives detailed installation and usage notes for several
common DCM installations. Between them, they highlight many important
features of the DCM. For full configuration information, please refer to Chapter
4, “Configuration options”.
3.1 General notes
Stand-alone DCM modules can be supplied with a touch-screen and
minibrowser as an option. This allows you to perform configuration tasks onsite. However, the touch-screen imposes some environmental restrictions on the
unit.
For all other DCM units, you will need console or network access to the DCM
to configure it for your installation. This is especially important if the DCM is
not to be part of a TCP/IP network whilst in use. As supplied, the DATA OUT
port runs the getty service, which you can use to access the console of the DCM
over a serial link. Alternatively, you can temporarily connect a computer to the
NETWORK port. It is recommended that you keep a connection to the DCM
available for maintenance and troubleshooting, even if the link is too slow for
transferring data.
3.2 The DCM as a data store
The simplest way to use a DCM is as a storage medium for digital data.
1. Connect the DCM to a digitizer or digital sensor.
2. Connect the DATA OUT port to a source of 12 V DC power.
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3. Connect the NETWORK socket to a computer as described in Section
2.4, “Connecting to a local network” and perform any necessary
configuration of the DCM and digitizer. You will be prompted for a
username and password: log in as root and use the password supplied
by Güralp Systems.
4. The DCM will immediately begin recording data into Flash memory as
it is received, and every so often data will be moved onto the internal
hard disk. At this point you can leave the DCM running without
assistance.
Data is stored in the Flash memory as a number of files in Güralp
Compressed Format (GCF) unless you have specified another option.
Once the memory becomes 75% full, files are automatically moved to
the hard disk until it is less than 50% full. (See Section 6.1, “File
systems” for details of the algorithm used.)
You can check that the DCM is receiving data either by monitoring the
Summary page of the on-board Web interface (see Section 5.7,
“Summary”), or from a command prompt using the command
gnblocks port-number
to find the number of GCF blocks received so far on a port. To see the
number of blocks recorded on all ports, type
gnblocks
5. If the internal hard disk is missing or becomes full, and you have chosen
the USB host option, the DCM will automatically look on the USB
interface for an external USB mass storage device.
6. To replace the internal hard disk, unclip the cover of the DCM and hold
down the lever button to bring the disk out from its housing.
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Slide the disk out and replace with another Lacie U&I drive, or any
brand of IDE / USB or IEEE 1394 2.5” drive you specify (at the time of
manufacture). You can do this at any time without losing data.
7. Plug the hard disk into any computer that supports the USB Mass
Storage standard using a standard USB cable. Newer Linux distributions
and Microsoft Windows XP have this enabled by default.
In Windows XP, you should see a series of Found new hardware
messages indicating that the drive has been recognised. A new disk drive
icon should appear in My Computer:
This process may take several minutes to complete.
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8. Double click on the drive's entry to browse the files inside and copy
them to your data store.
Alternatively, you can open the files directly from the USB disk using
Scream! or other GCF-compatible software.
9. When you want to remove the USB disk, double-click on the Safely
Remove Hardware button:
10.Choose the USB port attached to the disk, and click Stop.
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11.In the next window, check that the correct hardware is shown, and click
OK to confirm.
12.You can now remove the hard disk from the computer and reinstall it in
the DCM if required.
3.3 The DCM as a GCF data source
With a sufficiently fast serial link, you can instruct the DCM to send incoming
data directly to a GCF-compatible client. For example, Güralp Systems'
Scream! software allows you to display and record incoming data, as well as
change the settings of attached digitizers. You can do this in addition to
recording data on a local hard disk, or you can leave the hard disk uninstalled
and operate the DCM entirely over the network link.
This example shows a module communicating with a local PC over a dedicated
radio link. You could also use a simple serial cable to connect the DCM to the
PC.
1. Connect the DCM to a digitizer or digital sensor.
2. Connect the DATA OUT port to a source of 12 V DC power.
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3. Either use a computer connected to the NETWORK port to browse to the
Serial port configuration section of the DCM Web site, or log in to the
Linux console over the serial link.
4. Set the serial.2.service option to gcf_out. If using the Linux console, this
can be done using the command gcfgdbset (see Section 6.2,
“Command line tools”.)
Note: Beyond this point you will not be able to use the serial link to
access the Web configuration interface of the DCM. If you do want to be
able to do this, you should configure the serial link for PPP (see “PPP”
in Section 4.4) and run a Scream! server on the DCM. You will need to
assign the DCM its own IP address on your local network.
5. If you connected to the DCM by PPP, you will lose the network
connection at this point, because the DCM is now using the serial link
directly.
6. Open Scream!'s main window, and look under Local in the tree on the
left for the serial port which is communicating with the DCM. If it is not
shown, you may have to 'unfold' the tree to reveal it. The digitizer(s)
attached to the DCM will appear underneath the entry for the serial port,
and you can configure them from within Scream!. See Scream!'s
documentation for more details.
7. If no digitizer is shown, it may be that your software is not configured
correctly for the serial link. As supplied, the DCM uses a baud rate of
115200 on its CONSOLE port, with 8 data bits, no parity bits and 1 stop
bit, and no flow control.
For more information on how to use Scream! to display and manage data
streams, please see Scream!'s own documentation or the extensive on-line help.
Accessing the DCM command line through gcf_out
The gcf_out service provides a command-line terminal designed to be
compatible with Güralp Systems' SAM serial storage device. To access this
terminal from Scream!, right-click on the DCM's icon and select Terminal....
The SAM commands you can use are described in the SAM Operator's Manual.
You can also log in to the DCM's Linux operaing system through the terminal.
Enter the command
GETTY
and press ENTER. You will be presented with the login: prompt.
If you are not using Scream!, you can interrupt the GCF data stream and drop
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straight to the login: prompt by connecting direct to the serial port and typing
forcegetty
It may take several attempts for this to succeed.
Sensor arrays
Another possible reason for setting the DATA OUT port's service to gcf_out is
to allow several DCM units to work together and aggregate the inputs from an
array of sensors.
Here, DATA OUT ports with gcf_out as the service output data to the serial
inputs of another DCM or AM module, which aggregates them all and sends
them out over a network connection.
The DCM can handle multiple data sources with ease using the gcf_out service.
In practice, however, it is almost always preferable to set up a local area
network and use PPP over any serial links, so that GCF, Web and SSH traffic
can share the same connection. Setting up a fully networked array is slightly
more involved than using the simple gcf_in and gcf_out services, but affords
much more flexibility. See below for more details.
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3.4 The DCM as a network data hub
The most flexible way to operate the DCM is as a fully independent machine on
your local area network. To do this:
1. Connect Güralp digitizers to PORT A and PORT B as necessary, using
the serial data cable provided.
2. If you are using the DCM's USB capabilities, connect your external
hardware or computer to the USB socket.
Note: USB distinguishes between hosts and clients. The DCM can act as
either, depending on the options you specified at manufacture. If your
DCM is a host, you can attach external USB peripherals such as hard
disks. If it is a client, you can attach it to a computer, and it will appear
as a network interface.
3. Connect a Güralp combined serial/power cable to the DATA OUT port.
Make up a connector if necessary, and attach the power lines to a 12 V
DC power supply.
4. Connect the 9-pin serial socket to a computer for configuration.
5. Connect an Ethernet cable to the NETWORK socket, and set up the
network as described in Section 2.4, “Connecting to a local network”.
You should now be able to connect to the DCM's Web setup interface by typing
its IP address into any browser, e.g.
https://192.168.0.2/
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By default you can use either http: or https: URLs to access the DCM's Web
site. HTTPS is a secure variant of HTTP, which we recommend you use in
preference to avoid passwords being sent over the network in clear text.
Scream! and similar software applications should also be configured to use this
IP address to communicate with the module. If the DCM is using a static IP
address, you may assign it a name on your network (although you will still need
to use the numeric IP address in Scream!.)
The DCM also runs a SSH (secure shell) server, which you can use to access its
Linux command line over the network, just as if you had connected to it over a
direct serial link. The standard Linux program ssh and the freeware Windows
program putty are popular SSH clients.
If you do not wish to use the DCM's Web site, you can continue using the
gcfgdbset command to set other configuration options by name. For the
option names, you should refer to Chapter 4, “Configuration options” in the
DCM manual, where each name is given in italics with a description of its
action.
The command syntax to use is
gcfgdbset option-name new-value
The options will take effect immediately whenever possible. Some changes may
take some time to complete, since services may need to be restarted. The
gcfgdbset command performs only simple checks on the new value, so you
should check the syntax of the option carefully.
Communicating with digitizers
From the DCM, you can connect to the console of attached digitizers with the
command
minicom -n port-number
Alternatively, you can send individual commands to a digitizer with the
command
gcli port-number command
In these commands, port-number is the port number and port-name the
port device name to send the command to. To find out these, issue the
command serialmap:
Library version: libserialmap Version 1.0.5 with LIBGCONFIGDB
3 serial ports
Port 0, Key 7000, name Data out port, device /dev/ttySA0, baud
115200
Port 1, Key 7001, name Port B, device /dev/ttySA1, baud 9600
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Port 2, Key 7002, name Port A, device /dev/ttySA2, baud 19200
Each port will be listed, with its number (e.g. 0), name (e.g. Data out
port), and device (e.g. /dev/ttySA0).
Configuring digitizers
You can configure digitizers directly using the above commands. However, the
DCM also provides a Web interface to the digitizer's configuration options.
1. Choose the entry for the relevant port under Actions Digitizer Setup→
on the menu tree.
2. You can change all of the digitizer's configuration options from this
page. If you have attached a 6-channel digitizer, the page will reflect
this:
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