Technical data

Result Calling OB 120 has the following results:
Function no.
in
ACCU-2-L
Contents of ACCU 1
before after
1
2
3
Control word
Mask
Mask
Control word
New
control word
New
control word
Possible errors
•• Illegal function number in ACCU-2-L
•• One of the reserved bits in ACCU 1 (no. 3 to 31) is set to "1".
In the event of an error,
OB 31 (other runtime errors) is called. If
OB 31 is not loaded, the CPU goes to the STOP mode.
In both cases, an error ID is entered in ACCU-1-L.
Notes
•• You can scan the status of a control word with the following
program sequence:
1. Load the function number 2 or 3 in ACCU-2-L
2. Load the value ’0’ in ACCU 1
3. Call special function OB 120
4. Read out ACCU 1
•• You can determine the status of interrupt processing by reading
out system data word RS 131.
- RS 131 Condition codeword "disable all interrupts"
•• Instead of OB 120, you can use the operations IA and RA to
disable and enable process
interrupts as follows:
IA corresponds to :L KB 2
:L KM 00000000 00000100
:JU OB 120
RA corresponds to :L KB 3
:L KM 00000000 00000100
:JU OB 120
OB 120: Enabling/Disabling of Interrupts
CPU 928B Programming Guide
6 - 18 C79000-B8576-C898-01