Honeywell BC-200 Operation, Installation & Programming Manual page 117

Appendix
Connecting LCM with LEM
9.6.4.1 L :
OOP WIRING STYLES
Loops may be operated one of several modes – style 4, style 6 as well as style 7 (refer to diagrams below). Style
4 is an open loop arrangement while styles 6 and 7 are closed loop arrangements. Refer to section 0 for loop
configuration details and to section 9.4.2 for cabling requirements.
Style 4. (Open loop – does not return to the panel, non-redundant)
Port A (Channel A) 3810m maximum, 50 Ω resistance maximum.
Port B (Channel B) 3810m maximum, 50 Ω resistance maximum.
In style 4, the processor will poll both legs of the "loop" simultaneously through its own driver. If either leg is
shorted (wire-wire), the other leg is not degraded since it is operated from a separate driver.
Style 6. (Closed loop – returns to panel providing a redundant path for open circuit conditions)
Total Loop, 3810m maximum, 50 Ω resistance maximum.
In style 6, the processor polls the loop from one of the drivers (the B-side). If a failure (open circuit) is detected, it
will poll through both ends.
Style 7. (Closed loop with isolation modules providing a redundant path for short circuit conditions)
Total Loop, 3810m maximum, 50 Ω resistance maximum.
Maximum of 25 devices between isolation modules (Note: refer to install manual for more details)
In style 7, the processor polls the loop from one of the drivers (the B-side). If a failure (short circuit) occurs
between two isolation modules or the A or B ports of the LCM and an isolation module, the shorted section of loop
will be isolated and the processor will poll through both ends. Note that the A and B ports of the LCM also provide
short circuit isolation.
BC-200 Manual – P/N DOC-01-013 117