Micromod Micro-DCI: 53MC5000 PLC AND PRINTER INTERFACES - Manual (Page 31)

3.6 DDI-A AND DDI-B CHANNEL SETUP
The DDI-A/B channels each have up to 25 B-type control datapoints that are used for communica-
tions setup, read/write operations, and status. Seventeen of these B-type datapoints are config-
ured for each DDI channel by the user to define the PCS-PLC data transfer operations, e.g.,
starting PLC high/low memory addresses, data quantity transferred each transaction, communica-
tions baud rate, etc. The datapoints are described in detail in each PLC section of the book under
four catagories, which are APB Setup Bytes, PLC Control and Status Bytes, Read Control Bytes,
and Write Control Bytes. There is one exception, OPTO 22, which uses Digital I/O Control Bytes
and Analog I/O Control Bytes instead of the Read/Write Control Bytes. The remaining OPTO 22
bytes are similar to the other PLCs.
3.6.1 APB SETUP BYTES
The APB Setup Bytes contain communications control information such as baud rate and the se-
lected data format protocol. Also included in this catagory is the mode byte, which is used to iden-
tify the required PLC interface functionality. These bytes are applicable to all of the PLC operating
modes; they are illustrated in Figure 3-4.
3.6.2 PLC CONTROL AND STATUS BYTES
The PLC Control and Status Bytes contain information needed for both the read and write opera-
tions. This includes the scan time and, as applicable, the self address (Modbus slave mode) or net-
work interface address (Allen-Bradley mode). Also included is the setup error code, which is not
configured by the user but is a channel error code. In general, these bytes are applicable to all of
the PLC operating modes with some slight variations by PLC type; they are illustrated in Figure 3-4.
3.6.3 PLC READ CONTROL BYTES
The PLC Read Control Bytes contain information needed to transfer the data from the PLC to the
PCS. This information includes the PLC address, PLC starting memory address, the number of L-
type datapoints to be transferred, and the number of C-type datapoints to be transferred. Also in-
cluded are the PLC error code, communications error code, and error count, which are not
configured by the user but are status indicators for the read transaction. These bytes are not appli-
cable to the OPTO 22. They are applicable to all of the other PLC operating modes with some
slight variations. The PLC Read Control Bytes are illustrated in Figure 3-4.
3.6.4 PLC WRITE CONTROL BYTES
The PLC Write Control Bytes contain information needed to transfer information from the PCS to
the PLC. This information includes the PLC address, PLC starting memory address, the number of
L-type datapoints to be transferred, and the number of C-type datapoints to be transferred. Also in-
cluded are the PLC error code, communications error code, and error count, which are not config-
ured by the user but are status indicators for the write transaction. These bytes are not applicable
to the OPTO 22. They are applicable to all of the other PLC operating modes with some slight vari-
ations. The PLC Write Control Bytes are illustrated in Figure 3-4.
3.6.5 OPTOMUX DIGITAL AND ANALOG I/O CONTROL BYTES
The OPTOMUX Digital I/O Control Bytes and Analog I/O Control Bytes are applicable only to the
OPTO 22. These bytes are configured by the user; they are described in detail in Section 5,
OPTO 22 Mode.
Section 3. Product Description
DESCRP
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