INST.No.INE-863B KR2S
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Communication Interface
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Instruction Manual
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7-2
Data time interval
RTU mode: Less than 28-bit hours (2.8msec at 9600bps, 1.4msec at19200bps)
ASCII mode: Less than 1 second
When a message is sent, be careful that the time interval of data configuring one message does not exceed
the time shown above. If the time interval exceeds the time shown above, the receiving side (this unit)
judges that the transmission from a sender is finished and the data are processed as the reception of an
abnormal message.
In the RTU mode, message characters should be sent continuously, but in the ASCII mode, as the interval
between the characters is maximum 1 second, a master (PC) whose processing speed is comparatively
slow can be used.
7-3
Message configuration
The MODBUS messages have the following configuration for both of the RTU mode and the ASCII mode.
Slave address
Function code
Data
Error check
7-3-1
Slave address
Slave addresses should be set in advance in a range of 1-31. The master usually communicates with 1
slave. Only the slave corresponding with the slave address in the command message from the master
responds to that message.
The slave address “0” is used in messages (Broadcast) to all the slaves from the master. In this case, the
slaves do not return any response.
7-3-2
Function code
The function codes are the codes to be performed in the slaves and each data is roughly categorized as
follows. The table shows original functions of MODBUS and functions of our MODBUS instruments.
Summary of Contents for KR2S
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