Nor-Cal SDC15 Controller - Manual (Page 173)

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).
■ 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:
7-15
Chapter 7. CPL COMMUNICATIONS FUNCTIONS
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. 2000ms
(2) End of slave station transmission -
Transmission start time of master station = Min. 10ms
(1) (2)
(enable)
(enable)
(disable)
(disable)
Master station
Driver control
Slave station
Driver control
Transmission
line
(instruction
message)
Effective
data Effective
data
(1) End of master station transmission - Driver disable time = Max. 500 s
(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. 10ms
(4) End of master station reception - Driver enable time = Min. 10ms
End of master
station transmission End of slave
station transmission
(response
message)
(1) (4)
(2) (3)