Azbil C1M - Reception and Transmission Timing

7-17
Chapter 7. CPL Communication Function
7 - 7 Reception and Transmission Timing

Time specifications for instruction and response messages
The cautions below are required with regard to the timing of command message
transmission from the master station and response message transmission from the
slave station (this device).
z
Response monitoring 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 this device is two seconds ((1) in the figure below).
So, the response monitoring time should be set to two seconds.
Generally, when a response time-out occurs, the instruction message is resent.
z
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
Transmission line
Instruction
message
Response
message
Response
message
(1) (2)
(1) End of transmission by master station − Transmission start time of this device
= 2000 ms max.
(2) End of transmission by this device − Transmission start time of master station
= 10 ms min.

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
This device
Driver control
Transmission
line
Valid data
Valid data
End of transmission by master station End of transmission by this device
(1)
(4)
(2) (3)
(Instruction message) (Response message)
(1) End of transmission by master station − Driver disable time = 500 μs max.
(2) End of reception by this device − Driver enable time = Response time-out
setting (C70) or longer
(3) End of transmission by this device − Driver disable time = 10 ms max.
(4) End of reception by master station − Driver enable time = 10 ms min.