Advanced Micro Controls Inc. 1700 Series User Manual page 46

Overview
All PLC-5 processors have Block Transfer Instructions in their instruction sets. There are
five parts to PLC-5 BT Instructions. They are:
hý Module Address – The I/O rack, I/O group, and module slot numbers where the module
hý Control Block – The starting address of the five word block in memory that controls the
hý Data File – The starting address of the file that stores the data written to or read from the
module.
File Length – The number of words needed to store the data written to or read from the
hý
Continuous Parameter – Determines how often the block transfer is carried out.
hý
Module Address
The Module address is the I/O rack, I/O group, and module slot numbers where the module is
located in the system. These three numbers are entered separately in the block transfer instruction.
Control Block
The Control Block is a block of five words that control the actual transfer of data. The
address entered into the BT instruction is the first address of the block. The control block must
have an integer or BT data type and can be its own file or part of a larger file.
Each BT Instruction requires it own control block, even if multiple instructions
access the same module.
Data File
The Data File is the block of words that stores information read from or written to the 1700
module. The Data Address is the address of the first word used in the file. The data file must
have an integer or binary data type. It can be a separate file or part of a larger file.
File Length
Block Transfer Reads
The File Length is the number of words in your data file. When programming a BTR
instruction, you can set the Block Length to 00. This will reserve 64 words in the PLC-5
memory, but the module will only transmit the number of words necessary. The number of
words transmitted depends on the type of module and the value of the PLC Program parameter.
When programmable from the backplane, the modules transmit one additional word. Table 5.1
lists the number of transferred based on module numbers and PLC Program value.
PLC Program 1731 / 1741 1732 / 1742 1733 / 1743 1734 / 1744
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Chapter 5
is located.
Block Transfer.
module.
2 words
3 words
Table 5.1 1700 Block Transfer Read Lengths
PLC-5 BT Instructions
4 words 6 words
5 words 7 words
8 words
9 words
5-1