不同接口类型的HART猫
HART设备
此处找了些HART设备，作为例子，供参考：
（1）
中的：
接HART所用的终端电阻
250欧~1000欧
推荐：500欧
可参考：
http://www.mactekcorp.com/faq.php#0
的：
“6. What size HART loop series resistor do you recommend?
ANSWER: The HART specification allows for a series resistor range from 250 ohms to 1000 ohms with 500 ohms being the recommended value. Higher resistor values allow for a stronger HART signal but can reduce the power available to your instrument and impact reliability. Most installations stick to the lower end of that range, particularly when longer cable runs are used. The VIATOR will be able to communicate reliably with a series resistor as low as 150 ohms.”
USB转串口的普通的HART猫
普通的USB的HART猫，真的不支持HART设备
就像这里：
http://www.mactekcorp.com/faq.php#0
说的：
“4. My new notebook computer does not have a RS232 port on it – only USB. Can I use a USB to RS232 converter so that I can continue to use my RS232 VIATOR HART Interface?
ANSWER: Commercially available USB to RS-232 adapters typically do not meet the HART protocols strict timing requirements and generally don’t control the hardware handshake lines as required for HART communications.”
HART的硬件接线
正常的HART设备，在电源的正极和正极之间，去接电源线的正极和负极。
其中，对于设备的正极出来的线，串联一个电阻，所谓的终端电阻。
目的是，产生一定的电流，供hart信号使用。
然后对于电阻两端，再接上HART的信号线，比如HART modem的那两个挂针，如此，就可以通过hart modem（所转接出来的RS232信号），去接到PC上的RS232串口上了。
然后再在PC端，用相关的软件去测试。
转载请注明：在路上 » 【整理】HART硬件知识总结