Alias Modbus Device Id Functionality; Device Id Offset Functionality - Pepperl+Fuchs ICDM-RX/MOD Manual

ICDM-RX/MOD User Manual
Overview

1.7.1. Alias Modbus Device ID Functionality

The Alias Modbus Device ID functionality allows modification of device IDs only when messages are received
from Modbus masters. When configured, a Modbus message from a master with the specified device ID is
converted to the alias device ID, the message is then routed internally using the alias device ID. All responses
are returned to the master with the original received message device ID.
The following table demonstrates several device ID aliasing examples:
Received Alias Device
Device ID ID
1 10
50 5
100 254
10 10

1.7.2. Device ID Offset Functionality

The Device ID Offset functionality allows modification of device IDs when messages are transmitted to serial
Modbus slave devices. When configured, the Device ID Offset functionality will modify the device ID received in
the message to match the actual device ID range of the serial device(s). The device ID range is effectively either
increased or decreased depending on the serial port Device ID Offset configuration.
The following table demonstrates several Device ID Offset examples:
Device ID Offset Device ID
Mode
Off
Add-to-Msg-ID
Subtract-from-Msg-ID
It is highly recommended to take great care when configuring the Device ID Offset functionality. Verify the
following when configuring the Device ID Offset:
• Check for Device ID overlaps. Be certain that no two devices can have same device ID as recognized by the
internal Modbus Message Routing Handler.
• Check for conflicts with the Alias device ID configuration. The Device ID Offset configuration must coincide
with any Alias device ID configurations.
20
Routed Message
Device ID
Convert messages with received device ID 1 to 10.
10
Route message with device ID 10.
Convert messages with received device ID 50 to 5.
5
Route message with device ID 5.
Convert messages with received device ID 100 to 254.
254
Route message with device ID 254.
Invalid configuration attempt. No change to device ID is
10
performed.
Valid Message
Device ID
Offset
Range
0 1-255
50 1-205
100 101-255
Description
Valid Serial
Device ID
Range
Default mode. Device IDs are
1-255
unchanged.
Increase device ID range by 50.
Examples:
Device ID 1 is converted to 51
51-255
Device ID 10 is converted to 60
Device ID 120 is converted to 170
Decrease device ID range by 100.
Examples:
Device ID 101 is converted to 1
1-155
Device ID 150 is converted to 50
Device ID 225 is converted to 125
Description