Rockwell Automation 57C409 2 Channel Analog Input Module - Manual (Page 18)

4Ć2
Register 4 contains the common clock status. Bits 8 and 10 indicate
that the common clock is being driven by a module in the rack.
These bits must be set for the module to function correctly. Bit 6
indicates that this module is driving the common clock. Register 4 is
read only. Refer to figure 4.3.
bits
register 4 r r
Bit 10 Ć Common clock on
Bit ă8 Ć Common clock on
Bit ă6 Ć Common clock enabled
- - - - - - - r - - - - - -
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Figure 4.3 Ć Common Clock Status Register
Registers 5 and 6 contain the interrupt control registers. Each
channel may be programmed to interrupt independently of the other.
With the exception of bit 6 in each register, these registers are
controlled by the operating system and must not be written to by the
user. Refer to figure 4.4.
For this module to operate properly, the common clock must be
present on the backplane. The top LED on the module faceplate
indicates whether common clock is present. Note that the common
clock signal can be generated from a number of I/O modules,
including this module (57C409), 57C421, and 57C411. If this module
is to generate the common clock, bit 6 in either registers 5 or 6 must
be set. Refer to figure 4.4.
rw rw rw rw rw
register 5
Bit 15 Ć Interrupt flag
Bit ă7 Ć Interrupt enabled
Bit ă6 Ć Common clock enabled
Bit ă2 Ć + Interrupt allocated
- - - - - -
rw
rw -
- - - - - - -
rw rw - - -
- - -
rw rw rw
register 6
Interrupt Line ID
bits 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Figure 4.4 Ć Interrupt Control Registers