Micromod Micro-DCI: 53MC5000 PLC AND PRINTER INTERFACES - Manual (Page 25)

3.0 PRODUCT DESCRIPTION
3.1 DDI-A AND DDI-B MEMORY MAPS
As shown in Figures 3-1 and 3-2, there are two identical memory maps in the 53MC5000 PCS, one
for the DDI-A option and one for the DDI-B option. Each memory map has a set of contiguous L-
type datapoints and a set of contiguous C-type datapoints. There are 512 L-type datapoints (32
words or 64 bytes) and 64 C-type datapoints (64 words). In operations involving both L and C
data, the L data is transferred first.
The datapoint locations for the PCS memory maps can be summarized as follows:
Channel Type Datapoint
Range
DDI-A L L1536 - L2047
C C704 - C767
DDI-B L L1024 - L1535
C C640 - C703
3.2 TYPICAL PCS-PLC INFORMATION TRANSFERS
Figure 3-3 illustrates how information is read from a PLC to the PCS and entered into a memory
map (DDI-A is used here), and how information is written from the PCS to the PLC.
• 320 L-type contiguous datapoints (20 words) are read from PLC memory locations L000
through L319 and sent to PCS contiguous datapoint locations L1536 through L1855.
• 8 C-type datapoints (8 words) are read from PLC memory locations C00 through C07 and
sent to PCS contiguous datapoint locations C704 through C711.
• 64 L-type datapoints (4 words) are to be written from the PCS to the PLC. Four words are
counted up from the bottom to find the starting address of the datapoint information to be
transferred. The information transfer starts at location L1984. Datapoints L1984 through
L2047 are transferred to PLC contiguous locations L320 to L383.
• 3 C-type datapoints (3 words) are to be written from the PCS to the PLC. Three words are
counted up from the bottom to find the starting address of the datapoint information to be
transferred. The information transfer starts at location C765. Datapoints C765 through
C767 are transferred to PLC contiguous locations C08 to C10.
• Depending upon the PLC, the minimum transfer quantity of L-type datapoints is 8 or 16,
even if only a single L-type datapoint is to be transferred.
• The user is completely free to dedicate the L- and C-type datapoints to the reads and writes
as required; however, the total number of L-locations (512) and the total number of C-words
(64) must not exceed the maximums.
Section 3. Product Description
DESCRP
3-1