Campbell RTMS SYSTEMS Instruction Manual Download Page 16

SECTION 3.  RADIOTELEMETRY NETWORK COMPONENTS

3-4

not respond during this time, a “Bad Link” error
messages is returned.  The RFBase marks that
remote as bad and will return a “Bad Link”
message each time the computer attempts to
send packets to that site.  The RFBase will
continue to include the failed remote as part of
the polling process.  If the remote ever responds
to a poll, a “Communication restored” message
will be sent, and the RFBase will again accept
direct maintenance packets for that remote.

3.1.8  RF95T CONNECTIONS

The 9-pin Serial I/O connector is normally used
to connect the RF95T to the datalogger,
PS512M, or CH512R.  Table 3-4 describes the
9-pin connections.  The 10-pin rectangular
connector is for connection to the transceiver.
Table 3-6 contains the pinout for the radio to
modem cable descriptions.

TABLE 3-4.  Serial I/O Connector Description

Pin

Description

1

+5 V: Supply from external source

2

GND:  Ground

3

Ring:  Ring to datalogger

4

RXD:  Transmit from RF95T

5

ME:  Modem Enable from datalogger

6

Printer Enable:  Not used

7

Unload Enable:  Not used

8

Tape Enable:  Not used

9

TXD:  Received by RF95T

3.1.9  RF95T CURRENT DRAIN

Quiescent

1.4 mA

Wait *

3-4 mA

Active

30 mA

* Waiting to respond to broadcast.

Usually the radio current drain is the relevant
factor in battery power calculations.

3.2  RF100/RF200 RADIOS

3.2.1  RADIO DESCRIPTION

The RF100 and RF200 are used in Campbell
Scientific's RF applications to transmit and
receive data blocks.  The radios shipped from
Campbell Scientific are secured on a mounting
bracket designed to fasten on the top of the RF
modem (see Figure 3-3).

The mounting bracket also supports a BNC
Jack connector from the radio.  The coax cable
that is required to connect the radio to its
antenna should be connected to the radio at this
BNC connector.  See Section 3.3 for more
information on the antenna cable.

The RF100/RF200 Radios are connected to the
RF modem by a special radio cable.  The first
10-pin connector on this radio cable has a red
and black wire coming out of the connector.
This is the 10-pin connector (labeled "radio")
that should be connected to the radio.  The red
and black power wires should be connected to
12V and Ground respectfully.  The second 10-
pin connector (labeled "modem") should be
connected to the RF modem.  Table 3-6
contains the pin out of this radio cable.

FIGURE 3-3.  RF100 On Bracket with Connector

Summary of Contents for RTMS SYSTEMS

Page 1: ...RF FOR RTMS SYSTEMS INSTRUCTION MANUAL REVISION 3 95 COPYRIGHT c 1995 CAMPBELL SCIENTIFIC INC...

Page 2: ...ntability or fitness for a particular purpose CAMPBELL SCIENTIFIC INC is not liable for special indirect incidental or consequential damages Products may not be returned without prior authorization To...

Page 3: ...ttempts 2 3 2 6 Adding Stations to the Net Description 2 4 2 7 Radio Test Results 2 4 SECTION 3 RADIOTELEMETRY NETWORK COMPONENTS 3 1 The RF95T Modem 3 1 3 2 RF100 RF200 Radios 3 4 3 3 Antennas and Ca...

Page 4: ...rams and displaying current readings from the datalogger The requirements specific to a radiotelemetry network include The distance between radio stations should not be greater than approximately 25 m...

Page 5: ...ing the desired measurements Any field station can also operate as a repeater The only requirement is that the station s antenna must be able to communicate in all desired directions This may require...

Page 6: ...the field station s Normally all communication to the field stations originate at the base station Data retrieval remote programming and system analysis can all be done from the base station Equipmen...

Page 7: ...too long of a distance or an obstacle which impedes direct communication A repeater is not always required in a radiotelemetry network A field station can also function as a repeater Equipment Requir...

Page 8: ...e radio directly onto the bottom of the RF232T Secure the BNC connector from the radio s cable to its hole on the back of the RF232T See Figure 3 7 for assistance 3 Connect the radio to 12 V ground an...

Page 9: ...ast type of message about this station If the site is black no communication has been attempted yet If the site is red or blue than a warning or fault message has occurred If the site is green success...

Page 10: ...H SETTING box Separate the ids with a space When the BEGIN button is selected the entire link will be tested The signature of the remote site will still be returned An additional row of quality number...

Page 11: ...made 2 6 1 NETWORK HEALTH DISPLAY AND ERROR WARNING AND STATUS MESSAGES As remote sites are added to the network description they also appear on the network health display NetAdmin main screen The col...

Page 12: ...ough and will be retransmitted at a smaller size Over RF data is transferred as a stream of bits encoded into short and long periods of time between transitions We call the short time a 1T period and...

Page 13: ...d The following capabilities are important when using RTMS CR10T and RF95T modems A maximum depth of four repeaters can be used 150 is maximum number of remote RF95T CR10T site that may be used with a...

Page 14: ...Station ID 3 1 4 THE CARRIER DETECT LIGHT The Carrier Detect Light on the front panel of the RF95T has several purposes The primary function of the light is to indicate when data is being received or...

Page 15: ...e or last common repeater sending a single short broadcast to all remotes in the affected area Each remote RF95T upon receiving the broadcast checks the local datalogger for any computer bound packets...

Page 16: ...ed 9 TXD Received by RF95T 3 1 9 RF95T CURRENT DRAIN Quiescent 1 4 mA Wait 3 4 mA Active 30 mA Waiting to respond to broadcast Usually the radio current drain is the relevant factor in battery power c...

Page 17: ...he following steps will install a radio for a field or repeater station 1 Secure the radio and its bracket using the four screws from the RF95T Modem s lid 2 Connect the 10 pin connector with the red...

Page 18: ...TORS The most common cable type to connect a radio to the antenna is a coaxial RG 8A U cable Two connectors are required for each length of cable The connector for the radio is a BNC type connector Th...

Page 19: ...ort 3 4 2 ENCLOSURES Enclosures are needed to keep water and debris from damaging the data acquisition equipment Campbell Scientific Inc enclosures are designated as raintight and are designed to moun...

Page 20: ...to drop voltage and the other to raise voltage Alkaline batteries connected to the external port would be charged by the charging source which can cause an explosion CAUTION Do not use the external po...

Page 21: ...230 or 240 VAC if a small wiring modification is done 1 First disconnect any AC power 2 Lift the cover off the RF232 and locate the power supply P N 4918 as shown in Figure 3 8 3 Unscrew the four Phil...

Page 22: ...SECTION 3 RADIOTELEMETRY NETWORK COMPONENTS 3 10 FIGURE 3 8 Top View of the RF232T Base Station...

Page 23: ...until another description is made active even if RTMS is completely stopped If alternative communication paths exist i e a backup repeater in case the main repeater fails network descriptions utilizin...

Page 24: ...hould be large enough to accommodate the initial attempt and some retries 4 1 1 3 NETWORK HEALTH AND STATUS WARNING FAULT MESSAGES The RF specific messages are described in Section 2 6 1 of this manua...

Page 25: ...only be used with one site at a time and is not intended for unattended use While it is possible to have a station communicating with RTMS and GraphTerm at the same time more predictable behavior is e...

Page 26: ...er that is set with the switches in the RF95T The PATH parameter is the station number of the RFBase see above STATION NO followed by a colon As with the datalogger if the NetAdmin NBR parameter for t...

Page 27: ...The datalogger flags and ports may also be toggled Values can also be directly loaded into Input Locations Data can be collected for archiving while monitoring GraphTerm also supports the display of...

Page 28: ...ater or field site for single links Multiple site links may be tested by preceding the remote station ID with station ID from sites to be used as repeaters Separate the station ID numbers with commas...

Page 29: ...1001 1100X 100 0010 0110X 15 1111 0000X 58 0101 1100X 101 1010 0110X 16 0000 1000X 59 1101 1100X 102 0110 0110X 17 1000 1000X 60 0011 1100X 103 1110 0110X 18 0100 1000X 61 1011 1100X 104 0001 0110X 19...

Page 30: ...10 0111X 146 0100 1001X 189 1011 1101X 232 0001 0111X 147 1100 1001X 190 0111 1101X 233 1001 0111X 148 0010 1001X 191 1111 1101X 234 0101 0111X 149 1010 1001X 192 0000 0011X 235 1101 0111X 150 0110 10...

Page 31: ...the cable The two leads on the SC532 should be stripped and tinned for connection to a battery Most laptops have a 9 pin RS232 port so a 9 to 25 pin RS232 cable is needed to connect the computer to t...

Page 32: ...ts 95 dBm Signal Power SP TP AG PL CL where SP Signal Power dBm Power of the signal received TP Transmit Power dBm Rated output power of transmitting radio PL Path Loss dB Power lost over the distance...

Page 33: ...e frequency the stronger the radiation field However at higher frequencies more energy is absorbed by the surface The VHF and UHF frequencies can travel only a short distance between radio stations Th...

Page 34: ...er at the computer is responsible for naming the desired communication path with a setup string This setup string contains any repeater modem IDs and the destination modem ID in sequence After sending...

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