Omega DR130 SERIES, User Manual

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3-7
Overview and Specifications of RS-422-A/RS-485 Interface
3
Minimum Response Time
Because send and receive are done on the same line in the two-wire system, minimum response time
needs to be set. The minimum response time is the amount of time the RS-422-A/RS-485 module
waits in order for the host computer to be able to receive the data after it sends data. The time can be
set in the range from 0 to 100 ms. Set the time using the dip switch on the front panel of the RS-422-
A/RS-485 module to match the computer or the converter’s specification. (Refer to “3.5 RS-422-A/
RS-485 Interface Parameter Setting Procedure.”) Note that the minimum response time is, as the
name indicates, the minimum time for responding. Not all responses will take place in this time.
In the four-wire system, the minimum response time does not need to be set (set to 0 ms).
DR -> PC Data
Computer side
Transmission driver
DR side
Transmission driver
Data
Computer side
Transmission driver
DR side
Transmission driver
PC -> DR
DR -> PC PC -> DR
Terminator
Terminator
Active
Active
Response from the computer is too early
Delay after sending the terminator
Driver simultaneously becomes
output mode, and the data collides.
Active
Active
Insert appropriate time for waiting
Delay after sending the terminator
No time interval in which there is
data collision.
3.3 RS-422-A/RS-485 Interface Connection