Entering DB 1
The system program adopts DB 1 during a cold restart. The system
program checks to see if the inputs and outputs or IPC flags indicated
in DB 1 exist in their corresponding modules. If they are not present
there, a DB 1 error causes the CPU to go into the STOP mode and the
STOP LED flashes slowly. The CPU no longer processes your
program.
After you program DB 1 and the CPU accepts it during a cold restart,
the following rules apply:
••
Only the inputs and outputs indicated in DB 1 can access peripheral
modules via the process images (L.../T... ...IB, ...IW, ...ID, ...QB,
...QW, ...QD operations and logic operations with inputs and outputs).
Access to process image addresses not entered in DB 1 cause
addressing errors.
••
You can load peripheral bytes directly by bypassing the process
image using the L PB/L PY, L PW, L OY, L OW operations for all
acknowledging inputs, regardless of entries in DB 1.
••
You can transfer directly (T PB/T PY, T PW) to bytes 0 to 127 only
for the outputs indicated in DB 1. This is because the process image is
also written to during direct transfer. Writing to I/O addresses not
entered in DB 1 causes an addressing error.
••
Transfer without a process image :
Direct transfer to byte addresses >127 is possible regardless of the
entries in DB 1.
Direct transfer of byte addresses of the extended I/Os (T OY,
T OW) is also possible regardless of the entries in DB 1.
Multiprocessor Mode
CPU 948 Programming Guide
10 - 12
C79000-G8576-C848-04
Summary of Contents for CPU 948
Page 10: ...Contents CPU 948 Programming Guide 1 2 C79000 G8576 C848 04 ...
Page 32: ...Contents CPU 948 Programming Guide 2 2 C79000 G8576 C848 04 ...
Page 72: ...Data Blocks CPU 948 Programming Guide 2 42 C79000 G8576 C848 04 ...
Page 74: ...Contents CPU 948 Programming Guide 3 2 C79000 G8576 C848 04 ...
Page 154: ...Contents CPU 948 Programming Guide 4 2 C79000 G8576 C848 04 ...
Page 200: ...Contents CPU 948 Programming Guide 5 2 C79000 G8576 C848 04 ...
Page 308: ...Contents CPU 948 Programming Guide 7 2 C79000 G8576 C848 04 ...
Page 324: ...Examples of Parameter Assignment CPU 948 Programming Guide 7 18 C79000 G8576 C848 04 ...
Page 326: ...Contents CPU 948 Programming Guide 8 2 C79000 G8576 C848 04 ...
Page 370: ...Addressable System Data Area CPU 948 Programming Guide 8 46 C79000 G8576 C848 04 ...
Page 372: ...Contents CPU 948 Programming Guide 9 2 C79000 G8576 C848 04 ...
Page 486: ...Contents CPU 948 Programming Guide 11 2 C79000 G8576 C848 04 ...
Page 522: ...PG Functions via the S5 Bus CPU 948 Programming Guide 11 38 C79000 G8576 C848 04 ...
Page 524: ...Contents CPU 948 Programming Guide 12 2 C79000 G8576 C848 04 ...
Page 538: ...Contents CPU 948 Programming Guide 13 2 C79000 G8576 C848 04 ...
Page 546: ...List of Key Words CPU 948 Programming Guide Index 6 C79000 G8576 C848 04 ...