Carrier 48/50PD05 User Manual

47Main Base Board (MBB)See Fig. 16 and Table 19. The MBB is the center of theComfortLink control system. It contains the major portion of theoperating software and controls the operation of the unit. TheMBB continuously monitors input/output channel informationreceived from its inputs and from the Economizer Control Board(ECB). The MBB receives inputs from thermistors and transducers.The MBB also receives the Current Sensor inputs for compressorsand other discrete or digital inputs. The MBB reads spacetemperature (SPT) from either a T--55, T--56 or T--58 device andspace temperature offset (SPTO) from a T--56 device. SeeField-Installed Accessories section. The MBB controls 9 relays.IMPORTANT: The Main Base Board (MBB) has a 3-positioninstance jumper that is factory set to ‘1.’ Do not change thissetting.CEPL130346-01STATUSLENJ1 J2J4 J3J5J6J7 J8 J9J10CCNRED LED - STATUS GREEN LED -LEN (LOCAL EQUIPMENT NETWORK)YELLOW LED -CCN (CARRIER COMFORT NETWORK)INSTANCE JUMPER (SET TO 1)C07026Fig. 16 -- Main Base Board (MBB)48/50PD