7-16
Chapter 7. CPL COMMUNICATION FUNCTION
7 - 7 Reception and Transmission Timing
Timing specifications for instruction and response message
The cautions below are required with regard to the timing to transmit a instruction
message from the master station and a response message from the slave station.
Response monitor time
The maximum response time from the end of the instruction message transmission
by the master station until when the master station receives a response message
from the slave station is two seconds ((1) in the figure below). So, the response
monitor time should be set to two seconds.
Generally, when a response time-out occurs, the instruction message is resent.
Transmission start time
A wait time of 10ms is required before the master station starts to transmit the next
instruction message (to the same slave station or a different slave station) after the
end of receiving response message ((2) in the figure below).
Instruction
message
Response
message
Instruction
message
Response
message
Transmis-
sion line
• RS-485 3-wire system
(1) End of master station transmission -
Transmission start time of slave station = Max. 2000 ms
(2) End of slave station transmission -
Transmission start time of master station = Min. 10 ms
(1) (2)
RS-485 driver control timing specifications
When the transmission/reception on the RS-485 3-wire system is directly
controlled by the master station, care should be paid to the following timing:
(enable)
(enable)
(disable)
(disable)
Master station
driver control
Slave station
driver control
Transmission
line
(instruction
message)
Eective
data
Eective
data
(1) End of master station transmission - Driver disable time = Max. 500 μs
(2) End of slave station reception - Driver enable time = Response time-out
setup setting (
C70
) or greater
(3) End of slave station transmission - Driver disable time = Max. 10 ms
(4) End of master station reception - Driver enable time = Min. 10 ms
End of master
station transmission
End of slave
station transmission
(response
message)
(1)
(4)
(2) (3)