36
8-4-3. Specifying slave machine as talker from master unit
・
When the master unit sends a command requiring a response message to the slave unit and the
slave unit sends an acknowledge, a message having the structure shown in example 6 is sent to
the master unit.
<Example 6> Inquiring about the model of the PAR-A power supply unit controlled in address 1.
(Command: MS3)
ENQ
A
Block check characters
Address characters
S
T
3 ETX 1
E
ACK
A
ENQ
@ MS3 , 01 , 11 ETX 2
1
･･･
From the master unit to the slave unit.
･･･
From the slave unit to the master unit.
Transmission control characters indicating the
end of the message
Message characters
Transmission control characters indicating
The beginning of the message
<Precautions>
・
The service request function must be disabled when the master unit sends a command
requiring a response message to the slave unit. Otherwise, signal collision may occur in the
PAR-A transmission path.
8-4-4. Acknowledge or negative acknowledge to slave units
・
The master unit must send an acknowledge or negative acknowledge to the slave unit within 500ms
after completion of message transmission from the slave unit to the master unit.
<Example7>
ENQ @
Address character of the master unit
ETX 21
ACK @
･･･
From the slave unit to the master unit
MS3 , 01 , 11
･･･
From the master unit to the slave unit
If the master unit sends a negative acknowledge, the slave unit resends the same message to the
master unit.
<Example 8>
ENQ @
ETX 21
NAK @
･･･
From the slave unit to the master unit
MS3 , 01 , 11
･･･
From the master unit to the slave unit
ENQ @
ETX 21
MS3 , 01 , 11
･･･
From the slave unit to the master unit
<Precautions>
・
Unless the master unit sends an acknowledge or negative acknowledge to the slave unit, the
slave unit sends a message to the master unit twice.
8-4-5. Message structure list when using IF-41RS
Using a command for controlling the slave unit
