TM-9-1200-215-34&P Technical Manual for M109 Automatic Fire Control System (AFCS) Download
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TM 9–1200–215–34&P 2–5 (5) Discrete I/O Circuit Card Assembly (CCA). The Discrete I/O CCA consists of analog and digital circuitry that supports key communications protocols and formats used by the ACU to communicate with other AFCS hardware. The links provided by the Discrete I/O CCA include: Digital and discrete signal communications with the Display Unit (DU) Digital signal communications with the Dynamic Reference Unit (DRU) Digital signal communications with the Cab–Side VMS Modem Discrete communications with the Power Conditioning Unit (PCU) and Vehicle Intercom System (VIS) (6) 1553 Circuit Card Assembly (CCA). Interconnection of the ACU with the remainder of the AFCS is accomplished through the 1553 bus system. The 1553 CCA provides the interface between the ACU and the 1553 bus. (7) Tactical Communications Interface Module (TCIM) (CCA). The Tactical Communications Interface Module CCA allows direct connection between the ACU single–board computer CCA and the SINCGARS via the SCSI port of the computer CCA. (8) Backplane. The backplane of the ACU provides connectors for mating with the CCAs, and distributes signals and power among the CCAs. The chassis card slot allocations for the ACU component modules are depicted in Figure 2–2. A3 A5 A6 DISCRETE I/O A7 SERVO I/F CCA BACKPLANE CONNECTOR (POWER) POWER SUPPLY MODULE CPU CCA TCIM CCA 1553 I/F CCA A1 (J1) (J8) (J2) (J5) (J10) (J11) (J12) (J13) Figure 2–2. ACU Backplane Connectors (9) Solenoid Relay . The Solenoid Relay provides power to the Hydraulic Solenoid Valve and the Bypass Valve. The Hydraulic Solenoid Valve applies vehicle hydraulic pressure to the Azimuth and Elevation Servo Valves when adjusting the position of the weapon. The bypass valve allows hydraulic fluid to flow around the hydraulic motor when the hydraulic system is not pressurized. This allows the weapon to be hand cranked into position in the event the AFCS is inoperative. Change 1