Specifications

D2.1.2 PB1

The enclosed PBS1 program block manages the data traffic between the A250

and a PCS 9000. Thereby, the PCS sends orders to the receive buffer of the

programmable controller. The expander block transfers the data according to the

received orders. The synchronization of the data traffic is made via an order number.

The PCS writes a running number into the 1st. word of the receive buffer. After

processing the orders, the expander block writes the inverted number into the 1st.

word of the send buffer. At communication loss, this number is not written inverted.

The PCS recognizes thus an interruption of the communication. For the data

interchange, the expander requires a data area of 100 words as send and receive

buffer. Furthermore, a data area of 256 flag words (PCS DATA BLOCK) is required

for PCS data. The location of the data buffer is determined in FB201 that is selected

by OB1 during the 1st. scan. The following FBs are selected in PB1:

FB202:

Recognizes and initializes a new job package.

FB200:

Processes the received job package and synchronizes the data interchange.

All received orders are processed successively.

Furthermore, communication faults in OB1 are recognized via a time-out timer. If

the timer is not set anew by a missing job package, then the preset time (default

value 4 sec.) runs down and the A2.1 output is set. If a time-out fault appears, then

communication must be restarted via the E2.1 input.

D2.1.3 FB 200

FB200 has the task of selecting and executing the individual tasks from the received

job package. FBs 210 to 213 are selected depending on the order. Using the

COUNT_W data counter, the job package end is recognized and the FB 205

synchronization block is selected.

D2.1.4 FB201

This block initializes the location of the data areas. The P_DAT_OFF flag word

(default value MW 1000) is initialized with the start address of the PCS data area.

The PCS data area requires 256 flag words, whereby the location is driver-inde-

pendent. The P_REC_OFF flag word initializes the location of the send and receive

buffer. P_REC_OFF (default value MW 1256) must correspond to the address

selected in the driver. The send and receive buffer requires 100 words.

D2.1.5 FB202

FB 202 recognizes a new job package and initializes the corresponding pointers

that are necessary for package processing.

D2.1.6 FB205

FB 205 will be selected after the job packaget has been processed. Herewith, the

counters are reset. The received synchronization word is inverted and entered into

the send buffer.

PLC handling software