74 SOCOMEC - Réf. : 678 623 G GB
COMMUNICATION
The JBUS/MODBUS
®
used by the ATI
involves a dialogue using a master-
slave hierarchical structure. There are
two possible dialogues:
• the master communicates with a
slave (ATI) and waits for its reply
• the master communicates with all the
slaves (ATI) without waiting for their
reply.
The mode of communication is the
RTU (Remote Terminal Unit) using
hexadecimal characters of at least 8
bits.
According to the JBUS/MODBUS
®
protocol, transmission time must be
less than 3 silences, i.e. the emission
time of 3 characters so that the mes-
sage is processed by the ATI.
To correctly use information, the
following functions are important:
3: to read n words (maximum 128).
6: to write one word.
8: to diagnose exchanges between
the master and the slave via
meters 1, 3, 4, 5 and 6.
16 : to write n words (maximum 128).
LIST OF PARAMETERS TO BE DISPLAYED (FUNCTION 3)
Table of values on 2 words
The standard communications frame
consists of:
Slave address Function code Address Data CRC 16
NB:
When selecting slave address 0, a
message is sent to all the instruments
present on the network (only for func-
tions 6 and 16).
Comment:
The maximum reply time is 250 ms.
Decimal Hexa Number
Address Address of words Variable Units
768 300 2 I1 A/100
770 302 2 I2 A/100
772 304 2 I3 A/100
774 306 2 In A/100
776 308 2 U12Main V/100
778 30A 2 U23Main V/100
780 30C 2 U31Main V/100
782 30E 2 V1Main V/100
784 310 2 V2Main V/100
786 312 2 V3Main V/100
788 314 2 Freq.Main Hz/100
790 316 2 Active power (total) kW/100
792 318 2 Reactive power (total) kVar/100
794 31A 2 Apparent power (total) kVA/100
796 31C 2 Power factor 0,001
880 370 2 U12 Gen V/100
882 372 2 U23 Gen V/100
884 374 2 U31Gen V/100
886 376 2 V1Gen V/100
888 378 2 V2Gen V/100
890 37A 2 V3Gen V/100
892 37C 2 FreqGen Hz/100
894 37E 1 1MT V/100
895 37F 1 2MT V/100
896 380 1 AT s
897 381 1 DBT s
898 382 1 ROT s
Example
:
To read U31 gen = 228,89, the
following message should be sent:
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