FF H1现场总线通信研究

Study on FF H1 Communication Performance

为了研究基金会现场总线(FF H1)的底层通信,分析了理论编码波形和编码规则;基于Delta V系统构建FF H1网段,研究网段的实际通信情况,给出并评价网段的不平衡度、噪声、畸变和信号幅值;比较了不同电缆长度下网段的通信情况。实验表明:FF H1总线在长距离传输的抗干扰能力较强,信号幅值随电缆长度增加而衰减;关于终端电阻对H1总线的影响,在拔出终端电阻后,信号幅值和波形畸变明显增大,信号幅值超出了允许的调制范围。

For purpose of investigating into the bottom communication of FF H1 bus,the theoretical encoding wave and coding rule were analyzed; having Delta V control system based to construct FF H1 network segment and discuss its actual communication and present as well as evaluate the network segment's unbalance degree,noise,distortion and signal amplitude were implemented. Comparing the communication of different cable length shows that,the FF H1 bus has better capacity of resisting disturbance in long distance transmission;and the signal amplitude becomes attenuation with the increasing of cable length; and as for the termination resistor's influence on the H1 bus,when the termination resistor is pulled out,both signal amplitude and waveform distortion becomes increased and the signal amplitude exceeds modulation range allowed.