Ascii Driver (For Cpu 943/944 With Two Serial Interfaces Only) - Siemens SIMATIC S5-115U User Manual

Communications Capabilities
12.4 ASCII Driver (for CPU 943/944 with Two Serial Interfaces Only*)
CPUs 943/944 provide an ASCII driver for the second interface (SI 2). The ASCII driver regulates
data traffic between the main processor and the second interface.
The ASCII driver functions only if you make the appropriate setting in the high-order byte of
system data word 46 (see Table 12-7). Error messages are stored in the low-order byte of this
system data word.
Note
No other functions are possible (e.g. programmer/OP) when the ASCII driver is active.
Byte
High-order byte
Low-order byte
** Default value
* with the 816-1BB11 (CPU 944) operating system submodule
12-20
Table 12-7. Description of System Data Word 46
Contents
00
**
H
01
H
01
H
10
H
20
H
40
H
Description
PG/OP and SINEC L1 operation
ASCII driver
Error Check-Back signals
No ASCII driver
No CBS
No CBR
No CBS and no CBR
EWA 4NEB 811 6130-02b
S5-115U Manual