Private Device Id Range Setting; Shared Memory Functionality - Pepperl+Fuchs ICDM-RX/MOD Manual

ICDM-RX/MOD User Manual
Overview

1.8.1.2. Private Device ID Range Setting

This range defines the expected private slave device ID range on the serial bus.
• Modbus request messages received on this port that are within this device ID range will not be forwarded to
the Modbus network.
• All communication to device(s) in that range must occur between the Modbus master and slave(s) on that
serial bus.
• The private device ID range must not include public device(s) addressed by the serial master. Loss of
communication errors will result if this occurs. It is recommended to use either the Alias and/or the Device
ID Offset functionality to address those cases where a public device ID falls into the private device ID range.
• All received Modbus request messages that are not within the private device ID range or have been
previously detected on the serial bus, will be forwarded to the Modbus network via the ICDM-RX/MOD.
• Responses, including error messages such as timeouts, received from the Modbus network will be
forwarded to the serial master.
• The ICDM-RX/MOD has a built-in auto-detect algorithm for detecting private slave device(s) with ID(s) not
defined within the private device ID range. If a response from such a device is received on the serial bus,
the ICDM-RX/MOD will add that device ID to the private device list and will no longer route those messages
to the Modbus network.
Note: There is a potential race condition if a slave device ID is not within the private device ID range and exists
both as a public device on the Modbus network and as a private device on the serial bus. If this situation
occurs and the public device responds before the private serial device, the master would receive two
responses for that request, with the first response coming from the public device. If the public and
private device responded at the same time, the Modbus master could detect a corrupted response.
However, once the private slave device responds with a valid response, the auto-detect algorithm will
prevent forwarding of additional requests to the Modbus network.

1.9. Shared Memory Functionality

The Shared Memory functionality has been added to provide a simple and robust method for master-to-master
communication.
• The Shared Memory interface contains eight 200 Holding Register blocks and eight 160 Coil blocks.
• All Modbus masters, (Modbus/TCP, serial Modbus RTU/ASCII, and Modbus RTU/ASCII over Ethernet TCP/
IP), can read the contents of the Shared Memory blocks.
• Write access can be controlled to each Holding Register and Coil block. Each block can be configured to
provide all masters write access or be restricted to a port-specific serial master, a Modbus/TCP master or
an Ethernet TCP/IP master.
• The Shared Memory contents can be displayed and cleared via the embedded web pages.
• Diagnostics for each block include read, write and blocked write message counts.
• Blocked write messages are recorded in the Write Violation Log.
This table displays the supported Holding Register Block Function Codes.
Function Code
3 Read Holding Registers
6 Write Single Register
16 Write Multiple Registers
22 Write Mask Register
23 Read Write Registers
Description
23