User Guide
MES 1003 WMS
Doc no. 100837-MAN – Rev. E1 – Rev. date 2022-10
© Danfoss IXA A/S | Page 24
4.
IXA Modbus TCP/IP
4.1.
Introduction
This chapter explains how to establish and configure communication between the WMS and a controller using the
Modbus TCP/IP protocol.
4.2.
Example
Port number 502 and 1502
The supported protocol is Modbus TCP/IP ADU consisting of a MBAP header and a PDU, which is the standard default
format.
ModBus RECV:
00 01 00 00 00 06
00
01 00 00 00 05
ModBus SEND:
00 01 00 00 00 04
00
01 01 00
Table 11
Bold
MBAP header
2 bytes for MBAP transaction id – usually increasing
2 bytes for MBAP protocol – 00 00
2 bytes for data to follow
Italic
Unit id
Not used in Modbus TCP/IP
Underlined
PDU
In the above example:
RECV: Read Coils (01), starting Offset 0 (00 00), 5 coils (00 05)
SEND: Read Coils (01), coil values is 01 00
Table 12: Legend to Table 11
4.3.
Exception Answers
If parameters are out of range, not allowed, or unsupported functions are used, then an exception is returned as defined
by the Modbus standard. The standard defines that the Modbus function is returned with the high bit set followed by an
exception code. For example, an exception on the Modbus function 0x5 will return 0x85.
Example:
Attempting to enter Standby mode on a WMS already in Standby mode:
REQ:
00 05 00 00 00 06
00
05 00 00 00 00
Write coil (5), address 00 00, value 00 00
RESP:
00 05 00 00 00 03
00
85 03
Exception on write coil (85) – invalid parameter (03)
Table 13
