ProSoft Technology MVI69-103M - Manual (Page 78)

MVI69-103M ♦ CompactLogix or MicroLogix Platform Reference
IEC 60870-5-103 Master Communication Module
Page 78 of 131 ProSoft Technology, Inc.
November 3, 2008
Blocks -1 and 0 transfer status data from the module to the processor and they
contain no data when transferred from the processor to the module. Blocks 1 to
20 are utilized to transfer data stored or to be stored in the module's database.
These data blocks send data from module to the processor (monitored data
received from the devices on the serial network) and to send data from the
processor to the module (control data to send to the end devices). Block
identification codes 9901 to 9999 are used for special control blocks to control
the module.
Normal Data Transfer
Normal data transfer includes the transferring of data received by or to be
transmitted to the master drivers and the status data. These data are transferred
through read (input image) and write (output image) blocks.
Refer to Module Configuration for a description of the data objects used with the
blocks and the ladder logic required. The following topics discuss the structure
and function of each block.
Read Block
These blocks of data transfer information from the module to the CompactLogix
or MicroLogix processor. The structure of the input image used to transfer this
data is shown in the following table.
Offset Description Length
0 Read Block ID 1
1 Write Block ID 1
2 to (n+1) Read Data n
where
n = 60, 120, or 240 depending on the Block Transfer Size parameter (refer to the
configuration file).
The Read Block ID is an index value used to determine the location of where the
data will be placed in the CompactLogix or MicroLogix processor controller tag
array of module read data. The number of data words per transfer depends on
the configured Block Transfer Size parameter in the configuration file (possible
values are 60, 120, or 240).
The Write Block ID associated with the block requests data from the
CompactLogix or MicroLogix processor. Under normal, program operation, the
module sequentially sends read blocks and requests write blocks. For example, if
three read and two write blocks are used with the application, the sequence will
be as follows:
R1W1 R2W2 R3W1 R1W2 R2W1 R3W2 R1W1
This sequence will continue until interrupted by other write block numbers sent by
the controller or by a command request from a node on the 103M network or
operator control through the module's Configuration/Debug port.