5.3 MEMOBUS/Modbus Communications
298 YASKAWA ELECTRIC SIEP C710617 05F YASKAWA AC Drive GA700 Technical Manual
Figure 5.9 Message Example When Reading the Contents of Holding Register
■ Loopback Test
The loopback test uses function code 08 (Hex.) and returns the command message as a response message. This
test checks communication between the master and slave. The test code and data can use desired values.
Figure 5.10 shows examples of messages given out when the loopback test is done with the drive of slave 1.
Figure 5.10 Message Example When Doing the Loopback Test
■ Writing to Multiple Holding Registers
You can write the data that you set to the number of holding registers set in function code 10 (hex). You must
configure the number of the holding registers and each 8 higher bits and 8 lower bits in order in the command
message for the write data. You can write to a maximum of 16 holding registers.
Figure 5.11 shows example messages when you use the PLC to set Forward run in the drive of slave 1 with a
60.00 Hz frequency reference.
When you rewrite the parameter value with the write command through the H5-11 [Comm ENTER Command
Mode] setting, you must use the Enter command to save and enable the contents of the changes. Refer to H5-11:
Comm ENTER Command Mode on page 929 and Enter Command on page 302 for more information.
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