ABB TPU2000 Technical Manual page 362

TPU2000/2000R Modbus/Modbus Plus/ Modbus TCP/IP Automation Guide
Data transfer (read or write) is explained later in this document. Network Statistics is a count of each of the
node's good / bad transmission counts. If a bad transmission occurs, the nature of the failure is tallied on a table.
Local statistics are those from nodes on the same Modbus Plus network, Remote Statistics are those gathered
from nodes on other interconnected Modbus Plus networks.
An ABB protective relay has Modbus Plus "HOST" addressing implementation. An additional path entry is
required for address assignment for devices which are designed with Modbus Plus "HOST" implementation. An
ABB protective relay has the following Modbus Plus features available:
•
Place 32 Registers of Data in the Global Database for access by other devices.
•
Reply to 4X Read Data Requests from a Host or PLC Device.
•
Perform Operations when 4X Write Data Requests are sent by a Host Device.
• Respond to Local and Remote Network Statistics Requests.
•
Respond to Clear Local and Remote Local Statistics Requests.
In summary, the ABB protective relay responds to commands from a Modicon PLC as well as place data into the
Global Register buffer for retrieval from a host device.
Modbus Plus Node Addressing and Path Designation
Modbus Plus Node addressing for a Modicon PLC is determined by a thumbwheel switch or dipswitch
configuration on the appropriate PLC. Please reference the appropriate Schneider Electric Product Manual for
further information.
Figure 1 illustrates the Modicon PLC's resident data paths. The PLC has four data slave paths resident in its
device. An Additional Global Data Read Data Slave Path is available. It is through these paths that the PLC shall
obtain the relay information.
Figure 10. Typical Modicon PLC Modbus Plus Path Definition
The ABB Relay implementation host paths are shown in Figure 2. A comparison of the data paths shows the
similarities and differences between the PLC and ABB Relay implementation.
The ABB Relay however, requires an additional path added to its base address to complete the full Modbus Plus
address. As per the Figure 2 implementation, 8 data slave paths are incorporated within the relay. For a PLC to
access the data within the relay, a base address of the node and one of the eight path addresses must be given
for the address.
Program Master Path
(4) Data Slave Paths
Global Read Path
Program Slave Path
Modicon PLC
Global Write Path
(4) Data Master Paths
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