Issue/Rev. 0.1 (9/13) ║ MNFL003 • Page 23
master to delay twice between messages as long as the duration exceeds the speci-
fied delay).
4.12
How Characters are Transmitted Serially
When messages are transmitted on standard Modbus serial networks, each character
or byte is sent in this order (left to right):
With Parity Checking (8 bit word, 1 stop)
Start
1
2
3
4
5
6
7
8
Par
Stop
Without Parity Checking (8 bit word, 2 stop)
Start
1
2
3
4
5
6
7
8
Stop
Stop
4.13
Data Addresses in Modbus Messages
All data addresses in Modbus messages are referenced to zero; the first occurrence of
a data item is addressed as item number zero.
4.2
Modbus Functions
The following Modbus functions have been implemented in the microFlow.net Liquid.
Code Function
Description
01
Read Relay Status
Reads the binary data from the (read/write)
set of variables.
02
Read Input Status
Reads the binary data from the “inputs”
(read only) set of variables.
03
Read Integer Registers
(Read/Write Register Set)
Retrieves the current data from the request-
ed registers.
04
Read Integer Registers
(Read Only Register Set)
Retrieves the current data from the request-
ed registers.
05
Force Single Relay
Changes the state of a binary (read/write).
06
Write (Preset) Single
Register
Places a specific value into a (read/write)
register.
08
Loop Back Diagnostic Text
Diagnostic test message sent to the micro-
Flow.net Liquid to evaluate communications
processing.
Note:
Only the return Query Data diagnostic code is
supported.
15
Force Multiple Relays
Changes the state of multiple binary (read/
write).
16
Write (Preset) Multiple
Registers
Places specific values into a series of
consecutive (read/write) registers.
microFlow.net Liquid Modbus Communications Manual
Appendix
