Details of the Explicit Exchange Objects of the T_COM

At a Glance

This part presents the explicit exchange objects of the T_COM_MB type IODDT which apply to Modbus communication. It includes the word type objects whose bits have a specific meaning. These objects are described in detail below.

Sample variable declaration: IODDT_VAR1 of type T_COM_MB

Observations

In general, the meaning of the bits is given for bit status 1. In specific cases an explanation is given for each status of the bit.
Not all bits are used.

Execution Flags of an Explicit Exchange: EXCH_STS

The following table presents the meanings of the exchange control bits of the channel EXCH_STS (%MWr.m.c.0).

Standard Symbol	Type	Access	Meaning	Address
STS_IN_PROGR	BOOL	R	Reading of channel status words in progress	%MWr.m.c.0.0
CMD_IN_PROGR	BOOL	R	Current parameter exchange in progress	%MWr.m.c.0.1
ADJ_IN_PROGR	BOOL	R	Adjustment parameter exchange in progress	%MWr.m.c.0.2

Explicit Exchange Report: EXCH_RPT

The table below presents the meanings of the report bits EXCH_RPT (%MWr.m.c.1).

Standard Symbol	Type	Access	Meaning	Address
STS_ERR	BOOL	R	Reading error for channel status words	%MWr.m.c.1.0
CMD_ERR	BOOL	R	Error during command parameter exchange	%MWr.m.c.1.1
ADJ_ERR	BOOL	R	Error during adjustment parameter exchange	%MWr.m.c.1.2

Standard Channel Faults, CH_FLT

The following table presents the meanings of the bits of the CH_FLT status word (%MWr.m.c.2). The reading is performed by a READ_STS (IODDT_VAR1).

Standard Symbol	Type	Access	Meaning	Address
NO_DEVICE	BOOL	R	No device is working on the channel.	%MWr.m.c.2.0
1_DEVICE_FLT	BOOL	R	Not all of the devices providing the Modbus function manage this bit of the word.	%MWr.m.c.2.1
BLK	BOOL	R	Terminal block fault (not connected)	%MWr.m.c.2.2
TO_ERR	BOOL	R	Time out error (defective wiring)	%MWr.m.c.2.3
INTERNAL_FLT	BOOL	R	Internal error or channel self-testing	%MWr.m.c.2.4
CONF_FLT	BOOL	R	Different hardware and software configurations	%MWr.m.c.2.5
COM_FLT	BOOL	R	Problem communicating with the PLC	%MWr.m.c.2.6
APPLI_FLT	BOOL	R	Application error (adjustment or configuration error)	%MWr.m.c.2.7

Specific Channel Status, %MWr.m.c.3

The table below introduces the meanings of the PROTOCOL (%MWr.m.c.3) channel status word. Reading can be done via a READ_STS (IODDT_VAR1).

Standard Symbol	Type	Access	Meaning	Address
PROTOCOL	INT	R	Byte 0 = 16#06 for Modbus master function	%MWr.m.c.3
PROTOCOL	INT	R	Byte 0 = 16#07 for Modbus slave function	%MWr.m.c.3
PROTOCOL	INT	R	Byte 1 = 16#02 for Standby CPU function	%MWr.m.c.3

Command

The table below shows the meaning of the bits of the CONTROL word (%MWr.m.c.15). The command is made by a WRITE_CMD, e.g.: WRITE_CMD (IODDT_VAR1).

Standard Symbol	Type	Access	Meaning	Address
-	BOOL	R/W	Reset counter	%MWr.m.c.15.0
DTR_ON	BOOL	R/W	DTR signal (Data Terminal Ready) ON	%MWr.m.c.15.8
DTR_OFF	BOOL	R/W	DTR signal (Data Terminal Ready) OFF	%MWr.m.c.15.9
MB_TO_CHAR	BOOL	R/W	Modbus change to character mode (modem)	%MWr.m.c.15.14
CHAR_TO_MB	BOOL	R/W	Character mode (modem) change to Modbus	%MWr.m.c.15.15