serial coms

[Guest dave]

i am currently working on a project using a a-series a1s to display faults from a process machine on a e710 touch screen. which is easy enough the problem being that the plc already has a hmi plugged into the cpu so a rs422 card is being used. i have never wrote any code for comms and the current coding for networks and other comms is very badly documented in all off are plcs. The card used is a alsj71uc24-r4 (rs422) i have the operate manual for this but have only able been to grab a basic understanding of this. but wouldnt mind if some one could answer me a few questions i am reading the manual on the understanding that a connection like this needs to be set up as a dedicated protocol in no protocal mode is this correct from the setting up of the to/from instruction how do you define where the card is in the rack ie what part of the instruction and does the buffer memory address change depending where the card is. if not how do you check that buffer memory is not being used by a diffrent card if there is two cards the same in one plc rack also from reading the manual the transfer of code is done using data registers is this not possible with coils as most of the alarms set coils. if some one could help i would be very grateful also