Hollow shaft display with serial output
EP43RS / EP46RS
Date: 06/04/21
File: EP4RS_4.1_ing.doc
Rev: 4.1
Page: 8/12
The system (slave) transmits by an instrument MASTER on the serial line through a protocol type MODBUS
RTU words of 8bit; 1 stop bit and parity bit according to the
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constant which is set.
The physical interface is RS-485. Every EP4-_RS has an identifying address. The protocol is based on a
QUERY/RESPONSE structure: the slave devices reply to the queries with a message that contains the
identifying address and the requested data.
Further Information on the creation of two CRC bytes are available on
www.modicon.com
.
The activated MODBUS commands are:
0x03: multiple reading of registers
0x10: writing of several registers.
0x06 writing of one registers.
0x03 READING OF REGISTERS
To read the registers of the instrument, the master must send a query composed as follows (every element is
a byte):
ADDRESS | 0x03 | START_REG_HI | START_REG_LO | N_REG_HI | N_REG_LO | CRC_HI | CRC_LO
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START_REG_HI | START_REG_LO is the address at the starting 16 bit for the reading
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N_REG_HI | N_REG_LO is the number (16 bit) of the registers to be read
The instrument replies with the following message:
ADDRESS | 0x03 | NBYTE | DATA_1_HI | DATA_1_LO | DATA_2_HI | DATA_2_LO | … | CRC_HI | CRC_LO
DATA_1_HI | DATA_1_LO | DATA_2_HI | DATA_2_LO | … is the sequence of the data read.
NBYTE is the number of the given bytes that follow
DATA_1_HI | DATA_1_LO | DATA_2_HI | DATA_2_LO | … is the stream of data read.
0x10 WRITING OF REGISTERS
To write the registers of the instrument, the master must send a query composed as follows (every element is
a byte):
ADDRESS | 0x10 | START_REG_HI | START_REG_LO | N_REG_HI | N_REG_LO | NBYTE | DATA_1_HI |
DATA_1_LO | DATA_2_HI | DATA_2_LO |…… | CRC_HI | CRC_LO
The instrument replies with the following message:
ADDRESS | 0x10 | START_REG_HI | START_REG_LO | N_REG_HI | N_REG_LO | CRC_HI | CRC_LO
Connection scheme
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10 ÷ 30VDC positive power supply
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GND negative power supply
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RS+ RS485 serial port positive
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RS– RS485 serial port negative
Male connector: 4 pin M12x1 A-coding.
The pin configuration of both connectors is identical.
Please pay attention: an incorrect electrical connection could damage the unit.
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