Siemens SIMATIC Rack PC 840 - Page 138

Hardware Information
7-30
SIMATIC Rack PC 840 Manual
A5E00104826-03
Pin No. Designation Type * Pin No. Designation Type
C1 SBHE# O D1 MEMCS16# I
C2 LA 23 I/O D2 IOCS16# I
C3 LA 22 I/O D3 IRQ 10 I
C4 LA 21 I/O D4 IRQ 11 I
C5 LA 20 I/O D5 IRQ 12 I
C6 LA 19 I/O D6 IRQ 15 I
C7 LA 18 I/O D7 IRQ 14 I
C8 LA 17 I/O D8 DACK0# O
C9 MEMR# I/O D9 DRQ 0 I
C10 MEMW# I/O D10 DACK5# O
C11 SD 08 I/O D11 DRQ 5 I
C12 SD 09 I/O D12 DACK6# O
C13 SD 10 I/O D13 DRQ 6 I
C14 SD 11 I/O D14 DACK7# O
C15 SD 12 I/O D15 DRQ 7 I
C16 SD 13 I/O D16 + 5V V
CC
C17 SD 14 I/O D17 MASTER# I
C18 SD 15 I/O D18 0 V GND
# low active
Under normal conditions, the signals -SBHE, LA17 - LA23, -MEMR and MEMW
are operated as outputs (sending from the CPU). Only CPU boards which are
suitable for use as a master CPU for system bus access send and receive these
signals. A minus sign “-” in front of the signal name shows that the signal is LOW
active.