GB/T 15127-1994 Information processing system data communication twisted pair multipoint interconnection
Some standard content:
National Standard of the People's Republic of China
Information processing systems
Data communication -Twisted pair multipoint interconnectiens
GB/T 15127--- 94
1S0 8482-1987
This standard adopts the international standard 1S0) 8482-1987 "Information processing systems—Data communication -Twisted pair multipoint interconnectiens".
1 Topic content and scope of application
1.1 This standard specifies the physical media characteristics: for multi-point mutual alignment of twisted pair in two-wire or single-wire network topology, providing half-duplex or full-duplex data transmission capabilities respectively: a.
Binary signal and bidirectional signal transmission of interconnected endpoint systems; h.
Electrical and mechanical design of endpoint system branch cables and public down-line cables up to 5 (mm long); component measurement and recording of generators and receivers of dye circuit type within the endpoint system; d.
||The applicable data signal rate is up to 1Mbit/s. The electrical characteristics and measurements defined in 1.2 are very consistent with the point-to-point characteristics of twisted pair given in H7619. 1-3 This standard does not describe the physical connection of the whole speed, nor does it describe the functional interface characteristics, such as:
The number of interchangeable data circuits and control circuits; the type, size and pin allocation of the branch cable connector of the endpoint system; data and control signal encoding;
The relationship between the signals on the exchange circuit; d.
Synchronous or asynchronous Transmission method:
The quality of the signal transmitted and received,
1.4 This standard does not specify special environmental conditions, such as galvanic isolation, electromagnetic interference (FMI), radio frequency interference (RFI), and hostage safety. These may constitute the subject of future implementations. 1.5 This standard is primarily a component specification. It is not sufficient to specify satisfactory operation in all possible configurations. It is the responsibility of the implementer to ensure satisfactory operation in the intended configuration.
1.6 This standard may be combined with any appropriate combination of functional and additional environmental characteristics. Combined to meet the actual data transmission requirements in local or wide networks.
2 Referenced Standards
G17619 Electrical Characteristics of Balanced Dual-Stream Interface Circuits Commonly Used with Integrated Circuit Devices in the Field of Digital Communications 3 Standards
The definitions of the specified electrical characteristics are given in the Appendix (Supplement), approved by the State Technical Supervision Bureau on July 16, 1994
1995-0301 implementation
4 Symbolic representation of interchange circuits (see Figure 1)
GB/T 15127-94
The symbolic representation of the interchange circuit is in principle in accordance with the provisions of GB 7619. However, the generator in this standard includes an additional control to place the device in the working state, the non-working state and the high-impedance zero voltage state. The symbolic representation of this additional part is shown in Figure 1. Generator
Impedance according to
Balanced interconnecting cable
Generator exchange point
According to receiver loss point
Figure 1 Symbolic representation of interchange circuit
Receiver
V—Generator auxiliary output voltage between points A and B; Ve--Generator voltage between points B and C; R-cable termination resistor. Voltage reference interchange point (signal ground) V Generator voltage between points A and C; V,-ground potential difference; A, B and A', B interchange point Note: 1) Two five interchange points are shown in the figure. The output characteristics of the generator without any interconnection cable are specified in the \generator interchange point\. In the absence of a cable terminating resistor, the electrical characteristics to which the receiver must respond are specified at the "receiver interconnection point". ② Points C and C can be interconnected and, if required by national regulations, further connected to the protection trace. 5 Interconnection configuration (see Figures 2 and 3)
The interconnection configuration usually consists of a balanced trunk cable up to 500m long and several balanced branch cables. Each balanced branch cable connects each end system to the common trunk cable. The intervals between the branch cable connection points can be allocated as required, and a branch cable can be up to Sm long.
Each end of the balanced trunk cable is terminated by a terminating resistor. At each end system connection point, a branch/trunk cable connector should be used. This facilitates the generator/receiver load measurement defined in Section 6.1.2. The trunk cable is connected to each· The female connector of the cable should accommodate the terminating resistor.
If required by local regulations, all balanced cables can be shielded. It may also be necessary to extend the shielding to the branch/trunk cable connectors. Depending on the type of multipoint operation, a two-wire or four-wire interconnection configuration can be used. Figure 2 shows a two-wire multipoint configuration for half-duplex data transmission. Figure 3 shows a four-wire multipoint configuration for half-duplex or full-duplex data transmission. Haibei Nian
Endpoint system
Requires two-wire branch cable
GB/T15127-.-94
Endpoint system
Call symbol less ground
Figure 2 Two-wire multipoint configuration
Note: 1) The interconnection of the endpoint system is optional and depends on local regulations, +
Ruidian system|| tt||2) The branch cable shield is optional. When provided, it is connected to the endpoint system protective ground and may be further connected to the signal ground. 3) The branch cable shield is optional. When provided, it should be connected to the protective ground at one point. Interconnection of the main cable shield with the branch cable shield may be required.
Balanced Line
Planar Line Branch Cable
Biased Point System
Reliable Ground
Disconnection Point System
Figure 3 Four-wire Multipoint Configuration
Note: 1) The interconnection of the endpoint system signal ground is optional and depends on local regulations. And point system
2) The branch cable shield is optional. When provided, it is connected to the point system protective ground and may be further connected to the signal ground, 3) The main cable shield is optional. When provided, it is connected to the point system protective ground and may be further connected to the signal ground, 3) Cable shielding is optional. When provided, it should be connected to the ground at one point. Interconnection of the shield of the trunk cable with the shield of the branch cable may be required.
6 Loads on multipoints
Each end system is the load of the multipoint media. The load consists of a passive generator and/or receiver with associated internal wiring and a balanced branch inductor, as shown in Figures 2 and 3. According to the principle of multipoint half-duplex data transmission, only one generator can be in operation at any given time.
Successful operation requires load specifications for dc and ac loading. For dc loading, the component specifications in Chapters 8 and 9 should be selected so that the working generator can drive the interconnecting trunk cable, which is terminated at each end by a voltage of not less than 120Ω, and can drive 32 so-called unit loads (UI.). These 32 unit loads (UL) represent the total load of all end systems. The value of 1.0UL is defined in 6.1.1.
6-1 d.c. Load Specifications
The dc load specification limits the current of the upper generator to a practical value, based on which a hypothetical unit load (UL) is defined for the current/voltage measurement.
6.1.1 Definition of UL (see Figure 4)
1.0The UL value is defined as: when the voltage varies between -7V and +12V, the current varies between -0.8mA and +1.0mA. The corresponding current/voltage relationship is shown in Figure 4. The voltage range should take into account the output and offset voltage of the generator, the common mode and internal voltage of the receiver, and the power supply voltage. S
Figure 41. Current Limit of LJI.
6. 1. 2 UI of End System, Determined (See Figures 5 and 6) +2V
When measuring the current/voltage characteristic at the male pin branch/drop cable connector of an end system, the generator under test should be in an inoperative state and the measurement configuration is shown in Figure 5. The current/voltage measurement corresponds to the measurement of the GB7619 receiver input, that is, the voltage Vi (or Va) ranges between ~7V and +12V, while Vb (or V.) is maintained at 0V, and the resulting input current Ii (or Ii) should be maintained within the shaded range shown in Figure 4. These measurements are applicable under both conditions of the generator and/or receiver power supply being turned on and off. In order to determine U1. by measurement, the boundary slope of the current limit of a UI. (see Figure 4) should be modified to the minimum slope required to fully include the current/voltage characteristic, while keeping the -3V and +5V cutoff points unchanged. Then, the actual value of UL is equal to the larger of the two ratios of the actual current at 7V and +12V to the current of each L (see Figure 6 for determining IJ1.Figure 5 Input current/voltage measurement example 8UL value! .2UL GB/T15127--94 Figure 6 Determination of UL value 6.2 ac loading specification The ac loading caused by the endpoint system on the interconnected multipoint media affects the transmission characteristics. This effect depends on application parameters such as the type of calibrated cable and the data signal rate. Accordingly, the following measurements are provided as a guide and may be modified as necessary. See Appendix B (Examination Materials) Chapter B2.
6-2.1 Reflection Attenuation
The reflection attenuation of the termination system shall not be less than 20 dB. The measurement shall be made on the positive pin branch/trunk cable connector using a 120 Ω parallel test resistor. During the measurement, if a generator is present, it shall be inoperative. 6.2.2 Receive Distortion
For mark/space conversion at the applied data signal rate, the received signal distortion measured on the negative pin branch/trunk cable connector terminated with a 120 α resistor shall not exceed 25%. Note that in the case of twisted pair transmission media, the range of distortion related to the pattern is not too large for mark/space conversion measurements. Polarity and Effective Levels
The generator polarity and the receiver effective level correspond to the polarity and level of GB7619. Table 1 is taken from GB7619. Table 1 Receiver differential effective level
V\-V≤-0.3V
Data circuit
Control and timing circuit
"Off"
VA Vh'ta+0.3V
Space, 0
"On"
8 Generator characteristics
GB/T 15127-94
The generator part is measured in the working, low impedance state according to the following test method, and its measurement configuration is shown in Figures 7 to 10. The part can be operated on a single positive power supply.
The test can be carried out in one of two binary states, so the voltage amplitude specifications are represented by the symbols /V and /V, respectively. 8.1 Open circuit voltage V
When measured according to Figure 7, the voltage is:
between input terminals A and B, 1.5V≤1VI or I,1≤6.0Vp.
between terminals A and C and between terminals B and C,
iV| or |V| or /V| or |V. |≤6.0V.wwW.bzxz.Net
Figure 7 Open circuit voltage measurement
8.2 Offset voltage Vu
When measured according to Figure 8, the voltage is:
between the load center and terminal C, oV≤V. or. 3.oV, a
-binary state, difference /Vm—V%|≤0.2V. A
Figure & Offset Voltage Measurement
8.3 Output Voltage V with Termination.
When connected as shown in Figure 9 and the measurement voltage V is changed in the range of -7V to +12V, the voltage is: between output terminals A and B, 1.5VV.I or /V≤5.oV; a.
GB/T 15127-94
Binary state, difference /V, 1-[V|≤0. 2V. A
Figure 9 Output Voltage Measurement with Termination
1 Rise Time t and Unbalanced Voltage.
When the mark/space conversion voltage V_ is tested according to Figure 10, the rise and fall time between 0.1V and 0.9V_ at the output terminals A and B should be: a.
Where; tUL (unit interval) time,
V=[V.-Vl
The voltage formed due to the imbalance between the load center and the terminal C is: b.
V,≤o.4V (peak-to-peak value).
Change voltage
7V-.- 12 V,
9Receiver characteristics
CB/T 15127 --- 94
More than 10F rise time and unbalanced measurement block
Rise time;--the time duration of a unit interval at the applicable data rate: t,2,0.3r,V steady-state voltage difference; V-IV, induction
The receiver component is measured according to the measurement configuration shown in Figures 1 and 12. The components that meet these requirements are clock difference receivers. This receiver has high input impedance and a small input threshold transition region between -0.3V and .3V. The internal bias voltage does not exceed 0:-12
9.1 Input sensitivity (see Figure 11)
GB/T15127-94
Figure Input voltage range
Figure 12 Input balance measurement
Uncertainty
Uncertain Great Wall
(L-2V
The allowable range of input voltages VA and V appearing at the receiver input terminals A' and R' relative to the receiver terminal C' shall be between -7V and +12V. Within this allowable range, for any combination of receiver input voltages: the receiver shall present the expected binary state when the applied maximum input voltage V is +.3V or greater. In addition, the receiver shall not experience any damage when the test voltage at the receiver input terminals A' and C' or R' and C' is varied between -10V and +15V. 9.2 Input balance (see Figure 12)
GB/T 15127--94
The receiver input voltage/current characteristic and the balance of the internal bias voltages shall be such that when a differential voltage of VR ±0.6V is applied to each input through matching resistors equal to 1500 Ω, the receiver shall remain in the expected binary state as shown in Figure 12, where the input voltages VR and VRa range between -7V and +12V. When the polarity of Va is reversed, the opposite binary state is maintained under the same conditions. 10 FAULT CONDITION TESTING
To ensure that no damage occurs due to a single fault condition, the component shall be tested in the measurement configurations shown in Figures 13 to 15. 10.1 GENERATOR SHORT CIRCUIT (See Figure 13)
The generator shall not cause any damage by shorting the output terminals A and B to each other. A
Figure 13 GENERATOR SHORT CIRCUIT TEST
10.2 GENERATOR CONTENT TEST (See Figure 14)
The generator shall not cause any damage by shorting the output terminals A and B to each other. A
Figure 13 GENERATOR SHORT CIRCUIT TEST
10.2 GENERATOR CONTENT TEST (See Figure 14)
The generator shall not cause any damage by shorting the output terminals A and B to each other. 10.3 Generator Current Limits (See Figure 14) +12
When tested in accordance with Figure 14, by varying the test voltage from -7 V to +12 V (at a rate of change of 1.2 V/μs or less), the peak current fed into any connection of the generator shall not exceed 250 mA by varying the test voltage from -7 V to +12 V (at a rate of change of 1.2 V/μs or less) over the range of -7 V to +12 V. This criterion should not be interpreted as requiring a generator to source 250 mA, but rather that if multiple (source) generators provide this current, the sink generator is permitted to produce a combined current in excess of 250 mA [For additional information on generator competition, see Appendix B (Reference) B4.] Chapter 10.4 Transient overvoltage (see Figure 15) The measurement method in Figure 15 applies to both generators and receivers. A protection should be provided against transient changes that may occur in the GB/T 15127-94 interchange circuit when interrupted by the large current generated by the competing generator [for additional information, see Chapter B4 of Appendix B (reference)]. AA Generator or receiver Duration 15, duty cycle 1% Figure 15 Transient overvoltage test A passive generator or a receiver shall withstand without failure a pulse with a duty cycle of 1% and a duration of 15 ms, which is derived from a 25 V signal source with an internal resistance of 1000. The positive and negative pulses are applied between the A and C terminals and between the B and C terminals of the passive generator, and between the A and C' terminals and between the B' and C' terminals of the receiver. If a component experiences a transient breakdown during the application of a pulse, it shall be11 Environmental Limitations
For operation at data signal rates up to 1 Mbit/s on balanced switching circuits, the following conditions apply: The common mode voltage at any point in the switching circuit shall be in the range of 1 V to 10 V, however, in the case of generator competition, this range may be extended to 12 V (see Appendix B, Chapter B4 of the referenced part). The common mode voltage of the receiver is the worst-case combination of the following: I, generator-receiver ground potential difference (Vg, see Figure 1): h, longitudinal induced random noise voltage measured between the receiver A and (or H' and C) on the other side of the cable with the generator relays A, B and C on one side of the relay connected together: generator offset voltage V.
12 Component Compatibility
In some cases it is possible to produce generators and receivers that meet the requirements of GB 7619 and this standard (see Table 2). Table 2 is consistent with GB Compatibility of 7619
Generator and receiver
No damage
State overvoltage
Generator
Continuous output
Mark/space difference
GB/T15127
-7V-→-7V
10V-115V
25V~+25V
1.5V to 5.0V/540
Positive and/or negative
--7V～+7V
GB7619
12V-- +12V
2. 0V to 6. 0V/1000
Rise/Fall Time
Unbalance
Current Limit
Receiver
Minimum Sensitivity
Sensitivity Range
Unbalance
Internal Bias
Fault Detection
GB/T15127—94
Continued Table 2
GB/T15127
≤0. 4V Peak-to-Peak
≤250mA
±300mV
-7V～+12V
±600mV
GR #619
≤0. 4V Peak-drop
±300mv
10V~+10v
±?20mv
Three types
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