Instruction/ maintenance manual of the product B1474 Barnett Engineering
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RA DIO MO DEM B1474 OP ER A TION MAN UAL April, 1998 Manual Revision 4.1 (for Version 2.1 Hardware).
TA BLE OF CON TENTS FCC RE QUIRE MENTS ................... 2 1 IN TRO DUC TION ...................... 3 2 SPEC I FI CA TIONS ..................... 5 3 NO TA TION ........................ 7 4 OP ER A TION ........................ 8 5 SETUP PRO CE DURES .
FCC RE QUIRE MENTS This equipment generates, uses, and can radiate radio frequency energy and, if not used in accordance with the instruction manual, may cause interference to radio communications.
1 IN TRO DUC TION The B1474 Radio Modem provides a reliable method of sending 1200 baud data signals over radio or cable facilities. Digital information is converted to tone format for transmission over the communication channel. Received tones are converted back to RS232 digital format.
In di ca tors Modem status condition is indicated by front panel LEDs. The LEDs may be disabled to conserve power. B1474 BARNETT EN GI NEERING LTD. PAGE 4.
2 SPEC I FI CA TIONS GEN ERAL Trans mis sion Rate: 1200 Baud (Bell 202 sig naling) or V.23 if fac tory in stalled Trans mis sion For mat: 8 data bits, no par ity, 1 stop bit if mo dem buff er ing is se lected; oth er wise trans par ent Power Re quire ment: Op er ates from 12 to 30 VDC .
PTT Drop De lay: 0, 10, 20, 50, 75, 100 or 250 msec. Keeps trans mit ter keyed long enough to en sure squelch tail noise does n’t in ter fere with data at the re ceiv ing ter mi nal. Hand shak ing: Spec ifies the type of flow con trol used. 2/4 Wire: Se lects 2 or 4 wire ca ble op er a tion.
3 NO TA TION Throughout this manual, abbreviations will be used. These abbreviations are explained here for clarity. CD Carrier Detect COS Carrier Operated Switch CTS Clear To Send DCE Data Communicat.
4 OP ER A TION The B1474 operates from 12 to 30 VDC to provide an interface between two computer devices and the communications channel. In the descriptions below it is assumed that the sending device uses a DCE configuration.
B1474 BARNETT EN GI NEERING LTD. PAGE 9 FIGURE 1 MODEM TIMING USING RTS AND CTS.
Soft ware Hand shak ing Using XON / XOFF Basic operation and timing using XON / XOFF software handshaking are as follows: • The send ing com puter be gins send ing data.
– checks the chan nel, if this fea ture is en abled. If the chan nel is free, it as serts its PTT to power up the ra dio’s trans mit ter. If the chan nel is busy, it buff ers the re ceived data un ti l the chan nel be comes free. – pres ents MARK tone (car rier) onto the chan nel.
5 SETUP PRO CE DURES The semiconductors can be damaged by static discharge. Proper handling procedures must be followed . Do not touch any of the devices inside the modem, and work only in a static free, clean, and dry environment. (1) Re move The Top Cover Remove the two center screws on the top cover of the modem to release it from the base.
GND (Chassis) Pin 1 TXD Pin 2 RXD Pin 3 RTS Pin 4 (connect only if using hardware handshaking) CTS Pin 5 (connect only if using hardware handshaking) GND (Signal) Pin 7 CD Pin 8 The cable and housing on the DB-25S socket must be shielded to conform to FCC, part 15-J/A standard s for emissions.
Adjust R12 so that the modem waits when the channel is busy, and transmits when the channel is free. When the BUSY light is ON, the modem is waiting for the channel. To disable this feature, leave P1-9 unconnected and SW1.9 OFF. If Option 002 trunking software is used, set SW1.
To operate full duplex, leave SW2.8 OFF. To operate half duplex, set switch SW2.8 ON. If a 2 wire circuit is used, the modem will only operate half duplex. RTS Con trol SW3.1, when ON, will assert RTS continuously. This causes PTT to be asserted and transmit tones to be generated.
6 IN DI CA TORS The LED indicators on the front case are used to indicate modem status: RUN Power is on the modem. BUSY The modem is waiting to transmit but is held back by the squelch detector. RTS Request To Send from the computer is present or characters have been re ceived into the buffer.
B1474 BARNETT EN GI NEERING LTD. PAGE 17 7 CONFIGURATION RTS/ CTS DE LAY 20 X 50 3 msec 2 35 X 4 LEDS OFF X LEDS ON 1 LED CON TROL SWITCH 1 PTT DROP DE LAY 200 X 300 X X X 500 X X 1000 X X X 100 X X X.
B1474 BARNETT EN GI NEERING LTD. PAGE 18 BUFFER USE RTS/ CTS CON TROL X USE BUFFER 2 SWITCH 3 RTS ON 4 WIRE CA BLE X 2 WIRE CA BLE 4 RTS ON EX TER NAL RTS X RTS ON AT ALL TIMES 1 X 3.
B1474 BARNETT EN GI NEERING LTD. PAGE 19 +V 8 INPUT VO LT AGE GROUND TX WL TX WL TX RADIO 7 6 5 4 3 9 1 PIN SYMBOL DESCRIPTION GND 2 RX RADIO RX WL RX WL SQL PTT TRANSMIT OUTPU T , SINGLE ENDED TRANSM.
9 BOARD L AY OUT B1474 BARNETT EN GI NEERING LTD. PAGE 20.
Barnett En gi neering Prod uct War ranty WARRANTY STATEMENT Barnett Engineering Ltd . warrants that all equipment supplied shall be free from defects in material or workmanship at the time of delivery. Such warranty shall extend from the time of delivery for a period of one year.
11 AP PEN DIX A - OP ER A TION WITH A GE MARC V TRUNKING SYS TEM When ordered with the Option 002 trunking software, the B1474 will handle the special timing and control requirements of a GE Marc V trunking system. The following sections describe the connections to a trunking radio, and the slightly different operation of the radio modem.
B1474 BARNETT EN GI NEERING LTD. PAGE 23 FIGURE 2 MODEM TIMING FOR A GE MARC V TRUNKING SYSTEM USING RTS/ CTS HANDSHAKING.
Soft ware Hand shak ing Using XON / XOFF Basic operation and timing using XON / XOFF software handshaking in a trunking system is as follows: • The send ing com puter be gins send ing data. The for mat must be 8 data bits, no par ity, 1 stop bit. • Upon de tect ing data, the send ing mo dem per forms the fol low ing: – checks the chan nel.
No Hand shak ing Basic operation and timing with data buffering (no handshaking) in a trunking system is as follows: • The send ing com puter be gins send ing data.
An important point after buying a device Barnett Engineering B1474 (or even before the purchase) is to read its user manual. We should do this for several simple reasons:
If you have not bought Barnett Engineering B1474 yet, this is a good time to familiarize yourself with the basic data on the product. First of all view first pages of the manual, you can find above. You should find there the most important technical data Barnett Engineering B1474 - thus you can check whether the hardware meets your expectations. When delving into next pages of the user manual, Barnett Engineering B1474 you will learn all the available features of the product, as well as information on its operation. The information that you get Barnett Engineering B1474 will certainly help you make a decision on the purchase.
If you already are a holder of Barnett Engineering B1474, but have not read the manual yet, you should do it for the reasons described above. You will learn then if you properly used the available features, and whether you have not made any mistakes, which can shorten the lifetime Barnett Engineering B1474.
However, one of the most important roles played by the user manual is to help in solving problems with Barnett Engineering B1474. Almost always you will find there Troubleshooting, which are the most frequently occurring failures and malfunctions of the device Barnett Engineering B1474 along with tips on how to solve them. Even if you fail to solve the problem, the manual will show you a further procedure – contact to the customer service center or the nearest service center
