Simplex DC Line Communications Repeater Service

DC Line Communications Multiplex manual provides technical data about the 2120 0121 DC Line Communications Repeater CONTENTS DC Line Communications Repeater provides a means of extending a two wire direct current DC communication of the 2120 Multiplex System The output of the DC Line Communications Repeater hereafter referred to the DC Repeater duplicates output requirements of the DC communication board in the BMUX therefore ft at 4800 Baud 18AWG twisted shielded pair of wires applies to these signals same specifications DC Repeater no additional operational steps when a completely automatic device and therefore Up to five DC Repeaters may be used on a channel an additional feet for a total length of 60,000 feet provided 18AWG twisted shielded pair of wire is used The distance decrease with a decrease wire size Refer to Field Wiring Specifications extending channel details DC Repeater is an electronic printed circuit board requiring one unit of space in a cabinet When used as a stand unit where a power supply is included in the same cabinet it requires a minimum two unit box size AWO TWISTED WIELDED PAIR TO 10,000 FT BA FT BAUD AWG TWISTED TELEPHONE PAM AWG TWISTED WIELDED 10,000 FT BAUD FT BAUD AWG TWISTED TELEPHONE PAIR DATA SYSTEM WITH DC REPEATER 1 DC Repeater will both receive communication channel extension and it will receive replies from the transponders relay them to the BMUX from the BMUX and relay it to transponders connected SCC units connected the extension the DC Repeater outputs duplicates of the DC communication board signal the Repeater outputs 30 volts a Mark and 30 volts for a Space when repeating BMUX transmission and its output 30 volts for a Mark zero volts for a Space when repeating a transponder output on either side of the DC Repeater The number of transponders may be connected and its extension act as a single channel The DC Repeater does not increase or decrease number of transponders possible on a channel but only extends the distance that transponders may be installed the BMUX the communication 1987SimplexTimeRecorderCo Gardner 01441 0001 U S A REQUIREMENTS 24 volts DC 28 volts max 20.4 volts min milliampere maximum EARTH DETECT OUTPUT SIGNAL 20 ohms max 50K min CONDITIONS 122 relative humidity non condensing at 86 DC Repeater circuitry consists of standard printed circuit boards with integrated chips IC Therefore only handling normally given to that type of circuitry is required baud rate selector switch Sl is the only switch on the board The switch for the channel baud rate will be closed others will be open SETTING RATE MAINTENANCE DC Repeater has an earth ground when the earth detect circuit detects a ground on the transmission a 2120 monitor point on the lower number terminal output that will be normally OFF This output will be normally The output a ground is detected LED l will be illuminated the DC Repeater used as a stand alone unit a nearby monitor point should be used for transponders will be used as reporting units when the DC Repeater is a stand alone unit Repeater resets its circuitry at power application When the DC Repeater malfunctions perform the following its DC power for one minute TBI 3 or 4 Restore DC power Checkfor normal operation Replace the DC Repeater PC Board when the above steps do not correct the fault the DC Repeater the DC Repeaterwill to respond to the BMUX all the transponders connected communications failure the transmission extension DC Repeater and is referred to as BDAT The output data of the DC Repeater drives an extension of the transmission is referred to as TDAT The data on this line originates at the the regular channel communication connected is identical to the BMUX 30 volts for a Mark 30 output TDAT of the DC Repeater for a Space and it appears to transponders as a BMUX transmission When transponders on the transmis line 30 volts for a Mark 0 volts for a Space it will be detected received and retransmitted on the communica line by the DC Repeater the transmission l f l l I WORD 2 typical word of data is illustrated by Figure 2 with its retransmitted word Information being transmitted will be similar either word being transmitted delayed one half a data bit from the received word This delay permits the detection a valid START pulse A noise pulse whose length is less than one half of a bit length is dependent on selected rate will not activate the transmission circuit and no information will be transmitted valid START pulse A will exceed half a data bit triggering transmitter circuit B and start a baud generator baud generator will output triggering pulses at 1 data bit intervals Each of these triggering pulses C clock the data into the transmitter circuit The line data will be the nex bit being transmitted at this time the retransmission will be identical When it reaches a count of ten it enables a gate permitting the START PULSE DETECTOR when avalid start pulse was detected the incoming data A bit counter will be counting output of the bit next count to reset an inhibit signal that DIAGRAM 3 circuits permitting actions described are illustrated by block diagram Figure 3 a marking signal of 30VDC signal is applied to the transmission TDAT by the DC Repeater applied to the communication BDAT by the BMUX and a 30VDC polarity to indicate a Space START pulse This is received by all the BMUX transmits data it reverses DC Repeater The output of the receiver circuit is inputted to the start pulse on the line including the case of a valid START pulse will trigger the BDAT delay FF and activate the baud circuit which and character counter Once activated counter circuit inhibits the START pulse circuitry The baud will output a trigger pulse at each data bit interval This clocks the BDAT delay FF setting its output to repeat received signal DIAGRAM DC REPEATER 3 the character counter reaches 10 it enables a gate permitting eleventh baud pulse to remove the inhibit the start circuits The eleventh bit of the incoming word will be the STOP pulse Mark When this is clocked the transmitter delay FF it provides a Mark output until the next word is received TDAT circuitry works in a similar fashion with a START detection circuit of its own This detects when the trans line is shorted power on reset signal resets flip flops and counters when power is applied Simplex 6 67