Ch a pt er 1 0 De vic eN e t Com m unic at i on Mo d ul e A H 10 DN ET1 0 - 1 7○1 represents the control data that DeviceNet master sends and these data will be updated in theregisters starting from D1000 in real time. Meanwhile, ○2 represents the values in the registersstarting 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-timecontrol.10.5 Bit-strobe Command10.5.1 Bit-strobe Work PrincipleBit-strobe is one of the DeviceNet standard I/O transmission methods. The command length is fixedto 8 bytes, i.e. 64 bits. (Maximum 64 stations exist on the DeviceNet network.) And one bitcorresponds to one node. In the bit-strobe transmission method, the master does not send thecontrol data to the slave. But when the corresponding bit is set to OFF, the slave needs to reply theI/O data to the master; when the corresponding bit is set to ON, the slave does not need to reply theI/O data to the master.If the starting address for the output is D500, the corresponding relations between bit-stroberegisters and the nodes are shown as the following table.Bit-stroberegisterCorresponding network nodeb15 b14 b13 … … b1 b0D500 Node 15 Node 14 Node 13 … … Node 1 Node 0D501 Node 31 Node 30 Node 29 … … Node 17 Node 16D502 Node 47 Node 46 Node 45 … … Node 33 Node 32D503 Node 63 Node 62 Node 61 … … Node 49 Node 48Note:1. If the starting address for the output is set to D123 (which you can refer to section 10.6.2), thebit-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 tothe master after the corresponding bit is set to ON.b0b1b1 7 b1 5 b1 4b3 0 b2b1 8 ... ...... ... b1 6b3 1D501Node 0Node 1Node 2Node 14D500... ...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. Whenbit 0 and bit 1 are both OFF in D500, the node 0 and node 1 are both selected and they need tosend their own data to the master.
