Phoenix Contact IOL MA8 PN DI8, User Manual

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Technical appendix
4022_en_A PHOENIX CONTACT
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A Technical appendix
A 1 Modbus TCP interface
The IOL MA8 PN DI8 provides a slave-mode Modbus TCP interface that provides read
access to the Process Data Input (PDI) and Process Data Output (PDO) data blocks for
each IO-Link port.
– Write access to the PDO data block for each IO-Link port
– Write access to send ISDU requests to each IO-Link port
– Read access to ISDU responses from each IO-Link port
– Read access to the port information block for each IO-Link port
A 1.1 Modbus TCP function codes
This table shows the supported Modbus TCP function codes.
See “Modbus TCP configuration” on page 40 for process data block descriptions.
Table A-1 Function codes
Message type Function codes Maximum message size
Read holding registers 3 250 bytes (125 words)
Write single register 6 2 bytes (1 word)
Write multiple registers 16 (10 hex) 246 bytes (123 words)
Read/Write holding registers 23 (17 hex) Write: 242 bytes (121 words)