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1.8 Modbus RTU slave communication protocol
Module PL260 is conceived for the use with SCADA systems or Operator
panels via Modbus protocol RTU. Serial communication enables reading
and modifying of data on available memory areas, entering and visualizing
any data concerning the PLC. Module PL260 is provided with 3 serial
communication ports which are enabled to operate as slaves with
MODBUS protocol:
COM1 - RS485 available on connector plug-8 and on pins 31, 32 and 33.
EXP1 - RS232 available on pins 34, 35 and 36.
COM2 - RS232 available on connector plug-8.
Both serials support protocol modbus RTU as described below. Therefore
the module PL260 may be connected and may communicate with 3 master
devices at the same time.
Baud-rate Programmable
Format 8,N,1 (8 bit, no parity, 1 stop) (default)
Supported
functions
BITS READING (0x01, 0x02)
WORDS READING (max 30 word) (0x03, 0x04)
SINGLE BIT WRITING (0x05)
SINGLE WORD WRITING (0x06)
MULTIPLE BITS WRITING (0x0F)
MULTIPLE WORDS WRITING (max 30 word) (0x10)
Error codes ILLEGAL FUNCTION CODE (0x01)
ILLEGAL DATA ADDRESS (0x02)
ILLEGAL DATA VALUE (0x04)
Broadcast Simultaneous writing to all connected slaves using
address 0x00 and no answer by slaves.
Polling with
unknown slave
address
Polling using address 0xFF, any connected slave can
answer.
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