P R O F I B U S 技术培训 第三部分 安装与布线 This part gives an overview about installation and wiring techniques for PROFIBUS 第三部分 安装与布线

传输特点 (1) 高速 (H2), RS 485 依据 RS 485，异步 NRZ 传输 波特率从 9.6 kBit/s 到 12 MBit/s，可选 双绞屏蔽电缆 每段 32 个站，最多允许 127 个站 距离: 12 MBit/s = 100 m; 1.5 MBit/s = 400m; < 187.5 kBit/s = 1000 m 有中继器距离可延长到 10 公里 9 针, D 型插头 PROFIBUS offers 3 different versions of the transmission technology: - RS 485 used at FMS and DP - Fiber Optics (FO) for FMS and DP - IEC 1158-2 for PA The RS-485 technology is a proven technology that can be used in all areas of automation. It permits high protection against electromagnetic disturbances and is simple and easy to install. The PROFIBUS transmission speed (Baudrate) with RS 485 transmission is selectable in steps from 9.6 kBit/s to 12 MBit/s. All stations must operate at the same Baudrate. Basically, the transmission speed is selected via a switch at the master, and the slaves adjust themselfs to the baudrate of the Master. This feature is called Auto-Baudrate-Detection. With RS-485 technology, 32 stations can be connected to the same segment. If more stations shall be connected, repeaters must be used to extend to the network.

传输特点 (2) 低速 (H1), IEC 1158-2 同步 Manchester 编码, 31.25 kBit/s 本质安全 (可选) 和通过总线对站供电 (可选) 屏蔽或非屏蔽的双绞电缆 每段距离达 1900 米，用中继器可延长到 10 公里 最多 127 个站, 每段 10-32 个设备 (依赖于 EX-类型和供电消耗) The second version of the PROFIBUS transmission technology is the transmission technology according to the IEC 1158-2 standard. This technology is used for PROFIBUS-PA. The IEC 1158 technology permits powering of the stations over the bus on the same two wires where the data is transmitted. This is an option and is only used, if the field devices require this feature. Field devices with higher power consumption may be powered externally The IEC 1158 technology is in accordance with the international fieldbus standard IEC 1158-2. Depending on the ex-class and power requirements, 10 ... 32 stations may be connected in one segment. If more stations shall be used, various segments must be built. Each segment is coupled with a DP/PA coupler (or link) to the PROFIBUS-DP bus.

PROFIBUS 电缆要求 - IEC 1158-2 电缆设计: 屏蔽双绞电缆 导线面积: 0.8毫米2(AWG 18) 电缆设计: 屏蔽双绞电缆 导线面积: 0.8毫米2(AWG 18) 回路电阻: 44  / km 阻抗 （在31.25 KHz时）: 100  +/- 20% 衰减 （在39 KHz时）: 3dB / km 每单位长度的电容: 2nF / km The following line parameters describe a typical cable for IEC 1158-2 technology. Please refer to the Electronic Product Guide for all further details on the vendors of this cable. 对 IEC 1158-2 传输的电缆被列在 PROFIBUS 电子产品指南中

PROFIBUS 电缆要求 - RS 485 参数 电缆类型 A 电缆设计 屏蔽双绞电缆 浪涌阻抗 135 ... 165  电缆设计 屏蔽双绞电缆 浪涌阻抗 135 ... 165  回路电阻 110  / km 线径 0.64 mm 线截面积 > 0.34 mm 每单位长度的电容 < 30 pF / m This slide shows the electrical parameters of PROFIBUS RS-485 cables. Please note: The standard specifies two types: Type A is the preferred type, because this cable can be used with baudrates up to 12 MBit/s and permits longer distances even at low baudrates. Type B is an older cable which is limited to 1.5MBit/s. It is strongly recommended to use only type A cables. Please note that the standard allows the use of unshielded cables. I in practice however, it is strongly recommended to use shielded cables due to better EMC immunity.  PROFIBUS 电缆被列在 PROFIBUS 电子产品指南中。

 长度可以用中继器来延长 PROFIBUS 电缆长度 （对 RS 485） 波特率（ kBit/s） 9.6 19.2 93.75 187.5 500 1500 12000 线长（m, A类电缆） 1200 1200 1200 1000 400 200 100 The following transmission line lengths are reached with PROFIBUS cables type A. The total network distance may be extended by using repeaters up to a range of 10 km. The number of repeaters which can be used in series depends on the type of repeater and should be specified by the repeater manufacturer. Typically, not more than 3 repeaters should be used between two stations. The use of repeaters does not effect the baudrate.  长度可以用中继器来延长

9 针D 型连接器的针脚分配 （为RS 485用） 对 PROFIBUS-DP/FMS 提供的连接器类型是9 针 D 型连接器 插座部分被安装在设备上 如果其他连接器能提供必要的命令信号的话，也允许使用 All PROFIBUS devices with protection class IP 20 should normally use a 9-pin D-Sub connector. This is a preferred connection technology for PROFIBUS-FMS and PROFIBUS-DP. For devices with protection class IP 65 the standardization of PROFIBUS connectors is currently under preparation. Please note that all devices shall permit the mandatory signals including VP and GND. These signals are used for the bus termination or may be used to power fibre-optic converters.

拓朴 2 3 30 31 62 61 33 32 (PROFIBUS 支持总线型，树型和星型拓扑) 这里提供的拓扑是总线型拓扑 在总线的开头和结尾必须有终端 一段可以由最多 32 个站*组成 终端 终端 终端 中继器 站 1 2 3 30 31 With PROFIBUS it is possible to build networks in different topologies. The preferred network topology is a bus type topology. At lower baudrates it is also possible to build networks in star topology. For the use of star type topologies the maximum length of stubs must be taken into account. For the network design, it is important to distinguish between the maximal number of stations and the maximum number of bus loads in a segment. The number of bus loads in a segment is limited by the RS-485 technology and is restricted to maximal 32. It is important to know that repeaters do count towards the maximum bus load in a segment; even if they have no address assigned. 终端 中继器 62 61 33 32 * 注: 中继器没有站地址，但它们被计算在每段的最多站数中

安装 RS 485 (1) 电缆 A型电缆的总线终端 站 1 站 2 数据线 数据线 屏蔽 保护地 VP (6) 站 1 站 2 390  数据线 RxD/TxD-P (3) DGND (5) VP (6) RxD/TxD-N (8) (3) RxD/TxD-P (5) DGND (6) VP (8) RxD/TxD-N RxD/TxD-P (3) 220  数据线 RxD/TxD-N (8) 屏蔽 The following figure shows the cabling and termination of a PROFIBUS system using the bus cable type A. This is the preferred installation and termination method for all PROFIBUS networks. The termination of the network is normally located at the beginning and at the end of the segment. It should be ensured that the terminating resistors are always supplied with power. It is good practice to locate one termination at the master and the other one at the slave which is the last one at the bus at the end of the bus segment. Please note: If repeaters are used, it is good practice to locate one termination at the output of the repeater and the other one at the last station of the bus segment or at the input of the next repeater. 保护地 390  保护地 DGND (5) 电缆 A型电缆的总线终端

安装 RS 485 (2) 第一个站 最后一个站 总线终端 总线终端 VP VP 390  390  数据线 B B B 220  数据线 A A A 390  390  DGND DGND This slide shows the wiring of the PROFIBUS network. A B A B 站 2 站 3

RS 485 的屏蔽 / 接地  详细的安装指示在PROFIBUS-DP / FMS 的安装导则中说明， 订单号 2.112 主 从 从 接地线 接地线 接地线 For the use of PROFIBUS in industrial environment, a protection against electromagnetic disturbances should be carefully taken into account. Furthermore, a good potential equalization should also be taken into account. The figure shown on the slide is a recommendation to ensure that the network operates even in environments with heavy electromagnetical disturbances. All details regarding the PROFIBUS-DP and -FMS installation can be found in the Installation Guideline for PROFIBUS-DP and -FMS. This guideline is available at every User Group world-wide under order-no: 2.112. 数据电缆 数据电缆 接地电缆  详细的安装指示在PROFIBUS-DP / FMS 的安装导则中说明， 订单号 2.112

RS-485 传输的数据位顺序 每个八位二进数（１字节）按 11 位的顺序被传输 最小的有效位 (LSB) 被第一个发送 最大的有效位 (MSB) 被最后发送 每个八位二进数都补充三位，即开始、终止和奇偶校验位 此编码原理称 NRZ （即 Non Return to Zero） 2. 字节 The PROFIBUS RS-485 technology operates byte oriented. One byte is the smallest size of a possible message. The 8 user data bits of each byte are automatically extended with one Startbit, one Stoppbit and one Paritybit by the Hardware of the RS-485 Interface. This means that one byte (8 bit) is transmitted as 11 bits on the cable. This overhead ensures that all PROFIBUS messages are transmitted with high protection against undetected failures. All bytes of a PROFIBUS message must be transmitted without any slip (idle time) between them. All PROFIBUS messages have a hamming distance of HD = 4. 1. 字节 空闲 LSB MSB LSB 位顺序: 开始 1 2 3 4 5 6 7 8 奇偶 终止 开始 校验

信号电平 线 A 线 B 微分电压 A - B 1 2 1 = 数据传输开始 2 = 空闲段、无数据传输、总线终端终止的电平 This slide shows typical signals at the RS-485 transmission line. The difference A-B represents the real value of the bit sequence. 1 = 数据传输开始 2 = 空闲段、无数据传输、总线终端终止的电平

冗余性提高了系统的可靠性 系统冗余 介质冗余 每个测量点 两个设备 若干种接口给予了冗余系统的可能 光纤段给予了冗余电线的能力 FO coupler FO coupler PROFIBUS-DP 每个测量点 两个设备 PROFIBUS supports the set-up of redundant networks in two different ways: 1. The use of fiber optic components enables to build a redundant fiber optic ring as part of the network. 2. The use of two interfaces in one control system and the use of two different devices per measuring point ensure 100 % redundancy per measuring point. A specification of how to build redundant networks with RS-485 technology is currently under preparation and is expected to be available by End of 1998. FO coupler FO coupler 若干种接口给予了冗余系统的可能 光纤段给予了冗余电线的能力