Summary of Contents for Barnett Engineering B1474
- Page 1 RA DIO MO DEM B1474 OP ER A TION MAN UAL April, 1998 Manual Revision 4.1 (for Version 2.1 Hardware)
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Page 2: Table Of Contents
10 WAR RANTY STATE MENT ....21 11 AP PEN DIX A OP ER A TION WITH A GE TRUNKING SYS TEM ..22 B1474 BARNETT EN GI NEERING LTD. PAGE 1... -
Page 3: Fcc Re Quire Ments
This device was tested using a shielded cable connected to the data port. The unit must be operated using a shielded cable on the data line, with the shield grounded. B1474 BARNETT EN GI NEERING LTD. PAGE 2... -
Page 4: In Tro Duc Tion
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. - Page 5 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...
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Page 6: Spec I Fi Ca Tions
20, 35, 50, 100, 200, 300, 500, or 1000 msec. Al lows the trans mit ter RTS/CTS De lay: time to reach full power be fore data is trans mit ted. B1474 C to +50 BARNETT EN GI NEERING LTD. - Page 7 Spec ifies the type of flow con trol used. 2/4 Wire: Se lects 2 or 4 wire ca ble op er a tion. LED Con trol: Dis ables LEDs to save power. Equal iza tion: Full/Half Du plex: B1474 BARNETT EN GI NEERING LTD. PAGE 6...
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Page 8: No Ta Tion
DIP switch number one. XOFF ASCII 13h sent by a receiving station instructing the sending station to halt any transmission ASCII 11h sent by a receiving station instructing the sending station to resume transmission B1474 BARNETT EN GI NEERING LTD. PAGE 7... -
Page 9: Op Er A Tion
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. - Page 10 FIGURE 1 MODEM TIMING USING RTS AND CTS B1474 BARNETT EN GI NEERING LTD. PAGE 9...
- Page 11 The send ing com puter be gins send ing data. Data for mat must be 8 bits, no par ity, 1 stop bit. Upon de tect ing data, the send ing mo dem per forms the fol low ing: B1474 BARNETT EN GI NEERING LTD.
- Page 12 For no handshaking, non-buffered operation, set XON/XOFF signaling off, assert RTS (continuous) on, and buffering off. Do not connect the hardware RTS and CTS, and do not set RTS/CTS or PTT drop delays. B1474 BARNETT EN GI NEERING LTD. PAGE 11...
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Page 13: Setup Pro Ce Dures
PTT: The B1474 pro vides an open col lec tor driver for the ra dio PTT at P1-10. Squelch: The ra dio’s re ceive car rier op er ated switch (COS) can be mon i tored to de tect when the ra dio is re ceiv ing a sig nal by con nect ing the COS line to P1-7. - Page 14 SW1.9 OFF. If the opposite occurs, set SW1.9 ON. While the channel is busy, the modem will wait, sending only when the channel is clear. B1474 (connect only if using hardware handshaking) (connect only if using hardware handshaking) BARNETT EN GI NEERING LTD.
- Page 15 Set SW2.7 OFF to delay the received data for 5 msec, ON to delay the received data for 50 msec. Carrier detect delay should be less than the RTS/CTS delay at the sending end. Full/Half Du plex (Mode 3) B1474 BARNETT EN GI NEERING LTD. PAGE 14...
- Page 16 Place the top cover back onto the base and tighten the two center screws. (5) Ap ply Volt age Apply the proper voltage to the unit. If the LEDs are enabled, the run lamp will illuminate, indicating that power is available at the modem. B1474 BARNETT EN GI NEERING LTD. PAGE 15...
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Page 17: In Di Ca Tors
On when a mark is received and off when a space is received. On when a mark is transmitted. The LEDs may be dis abled to con serve power by set ting SW1.1 off. B1474 BARNETT EN GI NEERING LTD. PAGE 16... -
Page 18: Configuration
LOW = CHAN NEL FREE X HIGH = CHAN NEL FREE SEND/RE CEIVE (TRUNKING ONLY) PTT RE GARD LESS OF RFCTS X PTT ONLY WITH RFCTS B1474 TX LEVEL (INTO 600 OHMS) Ra dio (dBm) X -12 X -20 X 10... - Page 19 SWITCH 3 RTS ON EX TER NAL RTS X RTS ON AT ALL TIMES BUFFER USE RTS/CTS CON TROL X USE BUFFER RTS ON 4 WIRE CA BLE X 2 WIRE CA BLE B1474 BARNETT EN GI NEERING LTD. PAGE 18...
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Page 20: Con Nec Tions
TX RADIO TX WL TX WL RX RADIO RX WL RX WL DIG I TAL SYMBOL SIG GND B1474 DESCRIPTION INPUT VOLTAGE GROUND TRANSMIT OUTPUT, SINGLE ENDED TRANSMIT OUTPUT, BALANCED RECEIVE INPUT, SINGLE ENDED RECEIVE INPUT, BALANCED SQUELCH DETECTOR INPUT... -
Page 21: Board Lay Out
9 BOARD LAY OUT B1474 BARNETT EN GI NEERING LTD. PAGE 20... -
Page 22: Warranty Statement
(2) Exclusive Warranty The warranty set forth herein is the only warranty, oral or written, made by Barnett Engineering Ltd. and is in lieu of and replaces all other warranties, expressed or implied, including the warranty of merchantability and the warranty of fitness for particular purpose. -
Page 23: Op Er A Tion With A Ge Trunking Sys Tem
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. - Page 24 FIGURE 2 MODEM TIMING FOR A GE MARC V TRUNKING SYSTEM USING RTS/CTS HANDSHAKING B1474 BARNETT EN GI NEERING LTD. PAGE 23...
- Page 25 This configuration can buffer 500 msec worth of characters. To prevent internal data buffer overflow, it is important that the RTS/CTS delay timer be set to a value less than 500 msec and that the computer respond immediately to an XOFF command. B1474 BARNETT EN GI NEERING LTD. PAGE 24...
- Page 26 500 msec (RTS/CTS delay plus maximum channel busy time) or the maximum amount of buffered data is less than 50 characters. B1474 BARNETT EN GI NEERING LTD. PAGE 25...