MAN 06 033774 – technical_guide_ DIRIS_A40_A41_C.doc40/Z41 - B 13/27
CHAPTER 4 – RS 485 JBUS/MODBUS COMMUNICATION MODULE
The DIRIS A can be fitted with an RS485 JBUS/MODBUS communication module.
This module allows programming and visualizing the electrical values displayed by the DIRIS with a PC, a PLC or any other
system.
The RS485 connection is wired in series according to the EIA 485 with 2 active wire (+, -).
One RS485 line allows the connection of 31 slaves (DIRIS) over a distance of 1500 meters at 9600 bauds.
The number of slaves can be increase by using repeater(s), however, the maximum of slaves is 255 by communication canal.
It is recommended to use twisted pair type cable (LIYCY type ; minimum section: 0,34mm²). In a disturbed
environment or large network (in terms of length) we recommend using 1 shielded pair type LIYCY-CY (minimum
section: 0,34mm²).
Communication frame:
The standard communication frame is following:
According to the JBUS/MODBUS protocol, the transmission time must be less than 3 silences, i.e. the emission time
of 3 characters so that the message is processed by the DIRIS.
The available functions code are following:
- 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 ,2, 4, 5 and 6.
- 16 : to write n words (maximum 128)
-
The response time (time out question/answer) is 250 ms maximum.
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