Issue/Rev. 0.1 (9/13) ║ MNFL003 • Page 29
microFlow.net Liquid Modbus Communications Manual
Appendix
are contained in the next byte, again from left to right. As the bits are transmitted serially,
they flow from LSB to MSB (i.e., 20 through 27, 28 through 35, and so on).
In the last data byte, the status of relays 56 through 52 is shown as the byte value 1B
hex, or binary 0001 1011. Relay 56 is in the fourth bit position from the left, and relay
52 is the LSB of this byte. The status of relays 56 through 52 is expressed as ON-ON-
OFF-ON-ON. The three remaining bits toward the high order end are padded with zeros.
4.8
02 Read Input Status
Description
Reads the ON/OFF status of discrete “inputs” (read only binary references) in the mi-
croFlow.net Liquid. The maximum number of parameters supported by microFlow.net
Liquid is limited to 256 per query.
Query
The query message specifies the starting “input” and quantity of “inputs” to be read. “In-
puts” are addressed starting at zero: inputs 1 through 16 are addressed as 0 through 15.
An example of a request to read the status of inputs 1024 to 1033 from microFlow.net
Liquid 17 is shown below:
Query
Field Name
Example (Hex)
microFlow.net Liquid Address
0x11
Function
0x02
Starting Address Hi
0x00
Starting Address Lo
0xC4
No. of Points Hi
0x00
No. of Points Lo
0xOA
Error Check (CRC)
(calculated)
Response
The input status is packed in the response message as one input per bit of the data
field. Status is indicated as 0 = OFF; 1 = ON. The input addressed in the query
appears in the LSB of the first data byte. The other inputs follow toward the high order
end of this byte, and from low order to high order in all subsequent bytes.
The returned input quantity must be a multiple of eight; otherwise, the remaining bits in
the final data byte will be padded with zeros toward the high order end of the byte. The
quantity of complete bytes of data is indicated in the byte count field.
An example of a response to the preceding query appears in the following table.
Response
Field Name
Example (Hex)
microFlow.net Liquid Address
0x11
Function
0x02
Byte Count
0x02
Data (Inputs 1031-1024)
0xAC
Data (Inputs 1033-1032)
0x01
Error Check (CRC)
(calculated)
