GE P485 instruction manual Select ‘Add Command’ as described earlier, Query Column

FRAME AND COMMAND EDITORS

SPECIFYING A NEW COMMAND

Select ‘Add Command’ as described earlier.

This example is taken from a Modbus RTU implementation, which means that the frame will always consist of one byte for slave address, one byte for function code and two bytes for CRC. Furthermore, each command always consists of a query and a response.

The Modbus RTU specific frame objects are already in place and a data object is inserted between the function code and the CRC. These objects cannot be moved or deleted, however it is possible to add objects between the function code and the CRC.

		Figure 6-4: Specifying a new command
	First, enter a name for the command in the Command Name field (A) and an identifier in
	the Command ID field (B). If the command is allowed to be broadcast on the sub-network,
	check the Allow Broadcasting check box (C).
	The Query (D) field has the following characteristics:
Query		Column
	1: Slave Address.	2: Modbus Function Code	3: See below	4: Error Check field.
DisplayName	Slave Address	Function	Data	Checksum
	Protocol specific; cannot be altered.		(See below)
Object Type	Byte	Byte	Data	Checksum
	Modbus defines this object as a byte.		(See below)
Value	[SlaveAddress]	ID	User	User
	Linked to the actual ‘Slave	This value is linked to the	(See below)	Linked to “User”.
	Address’ parameter in the	Command ID field.		Determined by user at
	parameter window.			configuration by selecting
				the Error Check object in
				the parameter window.

P485 MODBUS TO PROFIBUS CONVERTER – USER GUIDE 6–3