63
6. Configuring the Gateway
Name of the Modbus command
Modbus quer
y
! Frame "
Slave no.
Function no.
No. of the 1st word
(
MSB / LSB
)
Number of words
(
MSB / LSB
)
CRC16
(
LSB / MSB
)
Modbus res
p
onse ! Frame "
Slave no.
Function no.
Numbe
r
of b
y
tes read
…Valuesof the words
(
MSB/LSB
)
…
CRC16
(
LSB / MSB
)
N.B. In all cases, the “Query / Slave Address” and “Response / Slave Address” elements are automatically
updated by AbcConf according to the node in which the command is located. Their values cannot be changed by
the user. In the same way, the “Query / Function” and “Response / Function” fields depend on the nature of the
Modbus command and cannot be changed by the user.
The operations to be carried out are more or less the same as those consisting of changing the default
commands. For the “Read Holding Registers” command, please see chapter 6.8.1 Replacing a Periodic Input
Data Element, page 48, and chapter 6.8.3 Increasing the Amount of Periodic Input Data, page 50. For the
“Preset Multiple Registers” command, please see chapter 6.8.2 Replacing an Output Periodic Data Element,
page 49, and chapter 6.8.4 Increasing the amount of periodic output data, page 53.
6.11.2. With a Generic Modbus Slave
Unlike the previous chapter, here we will be looking at adding and setting up a Modbus command which is
different from those configured by default with the LUFP9 gateway. We will benefit from this occasion to
exhaustively describe the fields allowing you to set up the management of communications for a command of
this sort.
Please see chapter 11 Appendix E: Modbus Commands, page 113, for a list of the Modbus functions supported
by the LUFP9 gateway. If you need to use a command which is not supported by the gateway, you can configure
one. A command of this sort is included in a specific element called “Transactions” or becomes a new Modbus
command in its own right. Please see the next chapter, § 6.11.3 Adding a Special Modbus Command, page 73,
for further details on this subject.
E.g. To illustrate the various operations to be carried out and the explanations given, we will be taking the
example of a Altistart starter, the ATS48, and a Modbus command recognised both by the gateway and the
ATS48. This is the “Preset Single Register” command, whose function code is 6 and which allows you to write
the value of a unique output word. This function will be used to periodically write the value of the ATS48’s CMD
command register, located at address W400 (address 400 = 16#0190).
Since the gateway’s default configuration already has 8 Modbus slaves, you will need to delete one of them,
such as the “TeSys U n°2” node, for example, and to add a new node in its place (see chapter 6.6 Deleting a
Modbus Slave, page 45, and chapter 6.7 Adding a Modbus Slave, page 46). Reminder: We strongly advise you
not to delete the “TeSys U n°1” node, as it contains the commands corresponding to the read and write services
for a parameter in a Modbus slave.