Chapter 10 DeviceNet Communication Module AH10DNET ○ 1 represents the control data that DeviceNet master sends and these data will be updated in the registers starting from D1000 in real time. Meanwhile, ○ 2 represents the values in the registers starting from D500 and these values will be transmitted back to DeviceNet master automatically. The two groups of data will be both updated in every scan period so as to achieve the real-time control. 10.5 Bit-strobe Command 10.5.1 Bit-strobe Work Principle Bit-strobe is one of the DeviceNet standard I/O transmission methods. The command length is fixed to 8 bytes, i.e. 64 bits. (Maximum 64 stations exist on the DeviceNet network .
) And one bit corresponds to one node. In the bit-strobe transmission method, the master does not send the control data to the slave. But when the corresponding bit is set to OFF, the slave needs to reply the I/O data to the master; when the corresponding bit is set to ON, the slave does not need to reply the I/O data to the master. If the starting address for the output is D500, the corresponding relations between bit-strobe registers and the nodes are shown as the following table. Note: 1. If the starting address for the output is set to D123 (which you can refer to section 10.6.2), the bit-strobe registers are D123~D126 instead of D500~D503. 2.
If the slave does not support the bit-strobe function, the slave will still reply the I/O message to the master after the corresponding bit is set to ON. ... ... Node 0 Node 1 Node 2 Suppose the starting address for the output is D500 and the slaves support the bit-strobe function. When bit 0 in D500 is OFF, the node 0 is selected and it needs to return its data to the master. When bit 0 and bit 1 are both OFF in D500, the node 0 and node 1 are both selected and they need to send their own data to the master. Node 14 10-17 Bit-strobe Corresponding network node register b15 b14 b13 … … b1 b0 D500 Node 15 Node 14 Node 13 … … Node 1 Node 0 D501 Node 31 Node 30 Node 29 … …
Node 17 Node 16 D502 Node 47 Node 46 Node 45 … … Node 33 Node 32 D503 Node 63 Node 62 Node 61 … … Node 49 Node 48 D501 D500 b31 b30 ... ... b18 b17 b16 b15 b14 ... ... b2 b1 b0