Rockwell Automation 1771-PD PID MODULE (+DU) - Manual (Page 98)

Programming
Chapter 3
3Ć55
Block Transfer Instruction Overview
All programming data for the PID module must be contained in files
residing in the PC processor’s data table. The files are block transferred
to the PID module where they are stored and used to perform PID control.
Figure 3.16 and Figure 3.17 present a brief summary of block format
block transfer instructions and data table locations.
NOTE: For PLC-2 family processors, the address of the file to be
transferred in the address of the first word in the file. The file address is
stored in BCD in a storage word located 100 8 above the instruction’s data
address. The number of words transferred must vary according to the
number of words in any of the files. When the block length is set to the
default value, the PID module will control the block length for each
transfer. Otherwise, if a program is written that allows unequal block
length other than default to be enabled in the same scan, incomplete data
could be transferred.
Figure 3.16
Block Format Block Transfer Instructions
EN ąBLOCK XFER READ
DATA ADDR:
MODULE ADDR:
BLOCK LENGTH:
FILE: 030
100
01
110Ć 110
DN
0130
07
110
07
EN ąBLOCK XFER WRITE
DATA ADDR:
MODULE ADDR:
BLOCK LENGTH:
FILE: 030
100
01
110Ć 110
DN
010
06
110
06
A block transfer instruction is
programmed in the ladder diagram by
deptressing the [BLOCK XFER] key
followed by [1] (for a READ) or [0] (for a
WRITE). The appropriate read or write
block, as shown below will appear on the
industrial terminal screen.
Numbers shown are default values.
Numbers in shaded areas must be
replaced by userĆentered values. The
number of default address digits initially
displayed, 3, 4, or 5 will depend on the
size of the data table. Initially displayed
default values are governed by the I/O
rack configuration.
Data Address : First, possible address in accumulated value area of data table.
Module Address : Rack, module group, and slot number.
Block Length : Number of words to be transferred. (00 can be entered for default value or for 64 words)
File : Address of first word in the file. Storage location is 100
8 above the data address.
Enable Bit (EN) : Automatically entered from the module address. Set on when rung containing the
instruction is true.
Done Bit (DN) : Automatically entered from the module address. Remains on for 1 scan following
successful transfer. 11121