Communications and Network, 2013, 5, 1-4
doi:10.4236/cn.2013.51B001 Published Online February 2013 (
Communication Technology and Application of Seismic
Precursor Network Instrument
Jianguo Wang, Wei Wang, Huiqin Yao, Xun Gao, Mingdong Zhang
Earthquake Administration of Tianjin Municipality, Tianjin, China, 300201
Received 2012
In this paper, the communication technology of seismic precursor network instrument is introduced, including instruc-
tion format and returned information format of instrument login, status information acquisition, and current measured
data acquisition. The remote monitoring alarm software is based on this technolog y, and also introduced that the struc-
ture of monitoring information table, abnormal alarm index, and monitoring strategy. The application of the software
raises instrument running rate and observation data quality.
Keywords: Network Instrument; Communication Technology; Remote Monitoring Alarm
1. Introduction
Through digital seismic observation network projects,
Tianjin seismic precursor network, from network to the
station, distributed database to station, IP to device can
monitor and control precursor observation instrument
remotely. Realized gathering instrument data and real-
time monitoring instrument’s status and property, by
which remote change the parameters and adjust the
working status of instrument, and can control basic in-
strument calibration [1-3].
During seismic precursor network instrument running,
always following system halted, clock error and wrong
data and so on, having a bad effect on instrument running
rate and data quality.
For this reason, according stipulation on geoscience
observatory network in China, we compiled the software
to monitor network instrument remotely and alarm by C#,
to identify and solve problems in time and improve run-
ning rate and data quality of instrument [1-3].
2. Network Instrument Communication
Stipulation on geoscience observatory network in China
is a network communication interface enacted for pre-
cursor observation instrument. It detailed prescribes the
precursor network instrument’s communication interface,
device information, running function, data format, com-
munication protocol and access security control protocol,
etc. It is an essential communication protocol for network
precursor instrument [1-3].
The data communication of client and instrument is
conducted by Ethernet and Socket based on TCP/IP pro-
tocol. Client sends request to instrument, realizes the
control of instrument and exchange of data information.
Instrument accepts and responds the instruction from
client, then implements the co rresponding action to com-
plete the data information exchange with client; instru-
ment can be regard as server [1-3 ].
System. Net. Sockets namespace in C# provides re-
lated class for writing network application programs like
Socket, TcpClient, and Net Work Stream and so on.
Socket class is used in management connection, to re-
alize Berkeley sockets interface. TcpClient class is based
on the Socket class, allows creating and using TCP con-
nection. Net Work Stream class deals specifically with
data stream of network form, receipts object parameter of
Socket class, and operate network data access [1-3].
2.1. Detect Instrument Network Status
Using C# call ping command (ping -n 1 to
detect connection of network, it is an easy way.
In the output stream, “(0% loss)” indicates that the
network is smooth, “Ping request could not find host"
indicates that ping request could not find host, "Request
timed out or (100% loss)” indicates ping request timed
2.2. Login Instrument
Client and instrument establish connection through in-
struction mode, according to user name and password
authenticates iden tity [1-3].
Send instruction format: get /length+ID+lin+username
Copyright © 2013 SciRes. CN
+password /http/1.1
Among them, length: the instruction length word; ID:
instrument serial number; lin: user login command word;
username: user name; password: password.
Return message format: If the login and connect is
normal, return $ack\n; if the login and connect is abnor-
mal, return $nak\n; if the instrument receive the errone-
ous instruction, return $err\n.
Instrument login code:
// Namespace reference
using System. Net. Sockets;
// Instrument IP address
string IP= "";
// Instrument port
string Port="81";
// Instrument login instruction
string Instruction="get/42+X311JSEA0003+lin+user-
name +password /http/1.1";
// Create a TcpClient, connected to the instrument.
TcpClient Client = new TcpClient (IP, Port);
// Get client stream for reading and writing.
NetworkStream Network_Stream = Client.GetStream
// Translate the instruction message into ASCII and
store it as byte array.
byte[] byteCode = Encoding. ASCII. Get Bytes (In-
// Send the instruction message to the connected
Network_Stream. Write (byte Code, 0, byte Code.
// Store the response bytes in the buffer.
byte[] buffer = new byte[1024];
// Read the first batch of the TcpServer response bytes.
int result = Network_Stream. Read (buffer, 0, buffer.
if (Encoding. ASCII. GetString(buffer, 0, result).
Trim(). ToLower() == "$ack")
// Instrument login successful
// Get instrument status informatio n
// Get current measured data
2.3. Get instrument Status Information
Instrument status information includes instrument run-
ning environment, running results, abnormalities and
various controllable status information [1-3].
Send instruction format: get /length+ID+ste /http/1.1
Among them, ste: the command word to get instru-
ment status information.
Return message format: $message length of status in-
formation data packet\n content of status information
data packet\n ack\n
Content of status information data packet: length, in-
strument clock, clock status, instrument zero, DC power
supply status, AC power supply status, self-calibration
switch status, zero switching status, the number of events
triggered, abnormal alarm status and custom status.
The content and format of instrument status informa-
tion sees Table 1.
For example:
Send instruction to get instrument status information:
get /19+X311JSEA0003+ste /http/1.1
Return data packet as following:
39 20100816145009 1 0.00 0 0 0 0 0 0 00
2.4. Get Current Measured Data
The current measured data is the latest 5-minutes sample.
If there is no sampling, get a recent sample [1-3].
Send instruction format: get /length+ID+dat+5 /http/
Among them, dat: data transfer command word.
Return message format: $message length of data pack-
et\n content of data packet\n ack\n
Table 1. The content and format of instrument status in-
Status information explanation
Length Record all the bytes contained in the
status information
Instrument clock Using the "YYYYMMDDHHMMSS"
Clock status "0" means GPS time service, "1" means
SNTP time service, "2" means internal
Instrument null point Custom real number
DC power status "0" means normal, "1" means abnormal
AC power status "0" means normal, "1" means abnormal
Self-calibration switch status"0" means close, "1" means open
Zero switching status "0" means close, "1" means open
Number of events trigge red The number of da y ev e n t s h a v e b e e n
Abnormal alarm status
One char, the corresponding 8 bits
from high to low represent power
failure, clock exception, unauthorized
access, event trigger, storage exception,
abnormal measured data, and custom
alert status
Custom Status Two chars 16 bit, each bit’s "0" or "1"
represent custom content
Copyright © 2013 SciRes. CN
Content of data packet: leng th, start time, station code,
instrument ID, sample rate, item number, item code 1,
item code 2, … , item code n, current 5 minutes observa-
tion data sorted by item order and sampling order.
In which, the length is byte count of the entire data
block, missing data is null.
For example:
Send instruction to get instrument current measured
data: get /21+X311JSEA0003+dat+5 /http/1.1
Return data packet as following:
189 144800 12001 X311JSEA0003 01 03 3127 3124
3125 54004.5 28502.9 -0009.67 54004.6 28503.6
-0009.77 54005.0 28504.2 -0009.78 54004.9 28504.1
-0009.76 54004.5 28504.6 -0009.84
3. Network Instrument Monitoring Alarm
Client monitoring alarm software finds out instrument
abnormal, sounds alarm and writes the instrument status
information and current measured data into oracle 10g
distributed database, by detecting instrument network
status, collecting instrument status information and cur-
rent measured data [4-6].
The work flow chart of remote monitoring alarm soft-
ware sees Figure 1.
Figure 1. The work flow chart of remote monitoring alarm
3.1. Design the Structure of Instrument
Monitoring Information Table
In the oracle database, the instrument monitoring infor-
mation table “Monitor” is used to store instrument status
information and current measured data.
The table structure sees Table 2 [7].
3.2. Abnormal Alarm Index
When the network instrument has the abnormal situation
as following, client software will sound alarm.
Ping instrument host, if return “Ping request could not
find host, Request timed out or (100% loss)”, indicate
that the instrument is no network.
Instrument clock and client computer clock have a
difference of more than 3 minutes, then need to adjust
instrument clock.
For example: On August 30, 2010, the operator on
duty found that Xu Zhuangzi wyy-1 meteorological in-
strument was faster 4 minutes than client computer,
then entered the instrument web page, ma-
nually modified the instrument clock and restarted it.
Note: client computer calibrates inner clock through time
Instrument DC power status is 1, indicates abnormal
presence, such as: DC power failure.
Instrument AC power status is 1, indicates abnormal
presence, such as: AC power failure.
Table 2. The structure of instrument monitoring informa-
tion table.
Field English
Name Field Chinese
Name Prime
Key Field
ITEM Current Item VARCHAR2(50)
DATA Current Data NUMBER(38,4)
Copyright © 2013 SciRes. CN
Copyright © 2013 SciRes. CN
Instrument abnormal alarm status takes a byte, the
corresponding 8 bits from high to low represent power
failure, clock exception, unauthorized access, event trig-
ger, storage exception, abnormal measured data, and
custom alert status. The any position is 1, indicates cor-
responding abnormal presence.
Using aggregate functions “max, min, sum, count”,
and group statement “group by”, to count measured data
that has been put in storage, to get max value, min value,
variation amplitude and average value [8,9].
If the variation amplitude is over than threshold, that
means abnormal situation. Such as well water level ex-
ceeds 1 m, well water temperature or auxiliary tempera-
ture of geomagnetic observation room exceeds 1, total
intensity of geomagnetic relative record, vertical com-
ponent or horizontal component exceeds 20 nT, air tem-
perature exceeds 20, atmospheric pressure exceeds 30
hPa and so on[8,9].
SQL statement as following:
Select unitcode, stationid, pointid, itemid,…, instru-
mentitem, max (instrumentdata), min(instrumentdata),
sum(instrumentdata), count (instrumentdata) from
qzprocess. monitor where startdate between to_date
('2010-8-1','yyyy-mm-dd') and to_date ('2010-8-31',
'yyyy-mm-dd') group by unitcode, stationid, pointid, ite-
mid,…, instrumentitem order by unitcode, stationid,
pointid, itemid.
3.3. Monitoring Strategy
Monitoring methods include manual mode and automatic
mode. Manual monitoring may monitor network instru-
ment at any time by click a button; automatic monitoring
need to set a monitoring interval, namely, every few mi-
nutes to monitor once.
The software uses multi-threading technology, assigns
a thread for each instrument, thus the execution time is
foreign to the number of instrument, reducing software
running time and improving software efficiency.
4. Conclusions
Using seismic precursor network instrument communica-
tion technology and oracle distributed database reading
and writing technology, we have developed monitoring
alarm software, which catches the instrument abnormal
information initiatively, makes a sound to alarm, and
provides the technology support for finding and solving
instrument’s problem, and improves the instrument’s
running rate and data quality effectively, and enhances
the Tianjin seismic precursor network running manage-
ment level [8,9].
On appraisal of national earthquake precursor network,
Earthquake Administration of Tianjin Municipality ob-
tained the first place on “System Running” and the sec-
nd place on “Output and Application” in 2009, obtained
the first place on “System Running” and the first place
on “Output and Application” in 2010, obtained the sec-
ond place on “System Running” and the first place on
“Output and Application” in 2011, achieved excellent
results, and produced good social benefit s.
5. Acknowledgements
This research was supported in part by methods research
and application for operation and management of re-
gional seismic precursor network in Tianjin under Grant
No. XH12004 and in part by earthquake precursor moni-
toring network and data management platform for re-
search based on WebGIS under Grant No. 09ZCKF-
SF00700 and in part by Tianjin seismic safety foundation
engineering “precursor instrument renovation project”.
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