Technical data

Interface to the User Program in the S7-200 CPU

2-11

SIMATIC NET CP 243-2 AS-i Master

C79000-G8976-C142/02

2.3.4 Control Byte (Output Register 8DO)

Meaning for the User Program

The user program controls the data exchange with the CP 243-2 using this

Structure of the Control Byte

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

PLC_RUN ASI_COM BS5 BS4 BS3 BS2 BS1 BS0

Description of the Bits

Table 2-2

Bit

Value Meaning

BS0..BS5 0 ... 63

dec.

Bank select bits for changing the bank in the analog module

(see Section 2.5).

ASI_COM 0/1 Job bit for the AS-i command interface (see Section 5.1).

PLC_RUN In the STOP mode of the S7-200 CPU, the CP must send defined values to

all AS-i slaves (see Chapter 3). Since the AS-i slave data are transferred

via the analog area and the S7-200 CPU does not set this area to ’0’ when

it changes from RUN to STOP, the CPU mode must be signaled to the

CP 243-2 using the PLC_RUN bit as follows:

0 Signal to the CP 243-2 that the S7-200 CPU is in the STOP

mode.

The CP 243-2 sends ’0’ to all AS-i binary slaves. The analog

value transfer to analog output slaves is interrupted. The

S7-200 CPU sets the bit automatically to “0” at a change from

RUN to STOP.

1 Signals to the CP 243-2 that the S7-200 CPU is in the RUN

mode.

The CP 243-2 sends the content of output bank 0 to all AS-i

slaves (see Section 2.4). The user program must set this bit to

“1” during startup (first scan).

Do not set the PLC_RUN bit permanently to “1” with the

S7-200 operating system functions such as “CPU

configuration/setting the outputs” or “force outputs”.