GE DS200SDCCG1ACA控制电路板卡
在主请求传输中，从地址表示请求被发送到的地址。在从属响应传输中，从属地址表示发送响应的地址。从属地址为0的主传输指示广播命令。广播命令只能用于存储设定点或执行命令。•功能代码：这是每次传输的第二个字节。Modbus定义1至127的功能代码。PQM实现了其中的一些功能。有关支持的功能代码的详细信息，请参阅第3节。在主请求传输中，功能代码告诉从设备要执行的操作。在从机响应传输中，如果从机发送的FUNCTION CODE（功能代码）与主机发送的功能代码相同，则从机按照请求执行功能。
n a master request transmission, the SLAVE ADDRESS represents the address to which the request is being sent. In a slave response transmission the SLAVE ADDRESS represents the address sending the response. A master transmission with a SLAVE ADDRESS of 0 indicates a broadcast command. Broadcast commands can be used only to store setpoints or perform commands. • FUNCTION CODE: This is the second byte of every transmission. Modbus defines function codes of 1 to 127. The PQM implements some of these functions. See section 3 for details of the supported function codes. In a master request transmission the FUNCTION CODE tells the slave what action to perform. In a slave response transmission if the FUNCTION CODE sent from the slave is the same as the FUNCTION CODE sent from the master then the slave performed the function as requested.
