Instruction Format (Partial); Read Do Output Coil Status; Read Holding Register - Ebyte MA02-AAC 2220 Series User Manual

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7.3 Instruction format (partial)

7.3.1 Read DO output coil status

Use 01 function code to read the output coil status, for example: read the status of two output coils
20
Device ModBus
function code
address
After sending the above command to the device via the 232 bus, the device will return the following values:
20
Device ModBus
function code
address
The status data 02 returned above indicates that the output DO2 is on.

7.3.2 Read holding register

Use 03 function code to read one or more register values, for example: read DO1 working mode.
20
Device ModBus
function code
address
After sending the above command to the device via the 232 bus, the device will return the following values:
20
Device ModBus
function code
address
The above 00 00 indicates that DO1 is in level mode.
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01 00 00
Register start address
01 01
Number of bytes of data
03 05 78
Register start address
03 02
Number of bytes of data
【2DI+2AI+2DO】MA02-AACX2220 User Manual
00 02
Number of output coils
02
Status data returned
00 01
Register read
quantity
00 00
Returned data
XX XX
CRC check code
XX XX
CRC check code
XX XX
CRC check code
XX XX
CRC check code
38