Numbers of IO modules in a rack in a 800xA System
Would you please tell me that in 800xA system, how much modules (IO modules) can be installed in one rack? And if I use profibus remote IO via CI840 then how much modules can be installed in modulebus right side of FCI?
If you are using the TB840/TB820 modules, the rules are basically the same as the Profibus segments.
Non-redundant controller allows for a total of 8 I/O segments / 96 modules total(1 local segment to the controller and 7 remote Cluster Modem segments)
Redundant controller allows for a total of 7 I/O segments / 84 modules total(No local segment supported because of redundancy so only 7 remote Cluster Modem segments)
Each TB840/TB820 cluster, in general can allow up to 12 I/O modules per segment (If you are using the redundant I/O bases (2 modules per Termination Base, then you are limited to 6x Termination bases w/ 2 modules per base or 12 in total). As indicated in the initial response to your question, this does vary depending on the I/O module type mix. In particular, the restriction is related to the maximum current draw on the I/O Module Bus. The module that has the largest impact on this draw is the DO820/DO821 (8 Channel Module with Electromechanical Relay: DO820 NO Relay / DO821 NC Relay). Although the S800 Module Bus can support 12 modules per segment, it appears that when using the DO820/DO821 modules, the the maximum number modules per segment if using only DO820/DO821 would be 10.
Additionally, something else to take into consideration when putting your installation together, for the electrical S800 Module bus ( Extension Cable Adaptors TB805, TB806 for single ) coming off of the controller or the TB840/TB820 or CI840 modem, the maximum physical length of the bus, including extension cables if used, is 2.5 m (8.2 ft.).