I-7000 Remote I/O 011

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Q.Who handle the direction of two-wire RS-485 network ?

Ans:The two-wire RS-485 network is a pairs of differential signal. So logically these two line equals to one data line. This data line can be used to transfer command and receive result both. This need a direction controller to handle the two-wire RS-485 network. The 7520, RS-232 to RS-485 converter, is a intelligent controller. It will automatically detect and control the direction of data flow. When the host computer send RS-232C command string, the 7520 set the direction of the RS-485 network in send mode and the 7000 modules can receive the host’s command string. After the command string is finished, the 7520 will set the RS-485 network in received mode to allow the 7000 modules to send the result to the host computer. Everything is automatically done, the user need not to care about the direction of data flow. The user only has to care that he should send the command string first then waiting for the result string next. The RTS-control signal of RS-232 is ignored. The 7520+7000 series module system don’t use RTS signal.

Written by David Chen 

Date:2002/12/24