Slave Mode

Slave MODE

MODBUS SLAVE contains 4 mapping arrays each with 9999 entries. The arrays are:

• Coils (0xxxxx) - cells of type BOOL

• Discretes Input (1xxxxx) - cells of type BOOL

• Holding Registers (4xxxxx) - cells of type WORD

• Input Registers (3xxxxx) - cells of type WORD

Lines 1..9999 correspond to the MODBUS address offset.

The default value for all cells in the arrays is NULL.

Reading values from arrays

Use the MODBUS_GET_COIL, MODBUS_GET_DISCRETE, MODBUS_GET_HOLDING, MODBUS_GET_INPUT, MODBUS_GET2_HOLDING or MODBUS_GET2_INPUT function block to locally read array values.

For remote reading of array values, use the standard MODBUS function via TCP connection.

NOTE: If you try to read a NULL value, the INVALID VALUE error is returned.

Write the values to the arrays

Use the MODBUS_SET_COIL, MODBUS_SET_DISCRETE, MODBUS_SET_HOLDING, MODBUS_SET_INPUT, MODBUS_SET2_HOLDING or MODBUS_SET2_INPUT function block to locally write array values.

Remote values can be writen to Coils and Holding arrays. For write, use standard MODBUS functions via TCP connection.

Application

MODBUS TCP SLAVE is useful if you need to provide a state of your own inputs for remote devices. For example, the switch on/off state of the button is provided for another device.

Similarly, if you need to set the status of the local relay from another device.

MODBUS_GET_COIL

Reads the appropriate COIL value from the internal modbus table of values.

in	OfsAdr	word		register address (1-9999)
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table
out	Q	bool		return value
out	R_TRIG	bool		for future use - not implemented
out	W_TRIG	bool		for future use - not implemented

MODBUS_GET_DISCRETE

Reads the appropriate DISCRETE value from the internal modbus table of values.

in	OfsAdr	word		register address (1-9999)
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table
out	Q	bool		return value
out	R_TRIG	bool		for future use - not implemented
out	W_TRIG	bool		for future use - not implemented

MODBUS_GET_HOLDING

Reads the appropriate HOLDING register value from the internal modbus table of values.

in	OfsAdr	word		register address (1-9999)
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table
out	Q	word		return value
out	R_TRIG	bool		for future use - not implemented
out	W_TRIG	bool		for future use - not implemented

MODBUS_GET2_HOLDING

Reads the two appropriate HOLDING registers value from the internal modbus table of values (lower register with higher weight).

in	OfsAdr	word		register address (1-9999)
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table
out	Q	dword		return value
out	R_TRIG	bool		for future use - not implemented
out	W_TRIG	bool		for future use - not implemented

MODBUS_GET_INPUT

Reads the appropriate INPUT register value from the internal modbus table of values.

in	OfsAdr	word		register address (1-9999)
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table
out	Q	word		return value
out	R_TRIG	bool		for future use - not implemented
out	W_TRIG	bool		for future use - not implemented

MODBUS_GET2_INPUT

Reads the two appropriate INPUT registers value from the internal modbus table of values (lower register with higher weight).

in	OfsAdr	word		register address (1-9999)
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table
out	Q	dword		return value
out	R_TRIG	bool		for future use - not implemented
out	W_TRIG	bool		for future use - not implemented

MODBUS_SET_COIL

Writes the appropriate COIL value to the internal modbus table of values.

in	OfsAdr	word		register address (1-9999)
in	VAL	bool		value to write
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table

MODBUS_SET_COILS

Writes the appropriate COILS value to the internal modbus table of values. In the range OfsAddrStart to OfsAddrEnd.

Always OfsAddrStart must be less than OfsAddrEnd.

in	OfsAddrStart	word		address start (1-9999)
in	OfsAddrEnd	word		address stop (1-9999)
in	VAL	bool		value to vrite
out	Err	bool		F = No error, T = occur any error
out	Err_ID	word		Error ID - see Error table

MODBUS_SET_COILS_ALL

Write all COILS value cross all registers 1 - 9999.

in	VAL	bool		value to write
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table

MODBUS_SET_DISCRETE

Writes the appropriate DISCRETE value to the internal modbus table of values.

in	OfsAdr	word		register address (1-9999)
in	VAL	bool		value to write
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table

MODBUS_SET_DISCRETES

Writes the appropriate DISCRETES value to the internal modbus table of values. In the range OfsAddrStart to OfsAddrEnd.

in	OfsAddrStart	word		address start (1-9999)
in	OfsAddrEnd	word		address stop (1-9999)
in	VAL	bool		value to write
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table

MODBUS_SET_DISCRETES_ALL

Write all DISCRETES value cross all registers 1 - 9999.

in	VAL	word		val to write
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table

MODBUS_SET_HOLDING

Writes the appropriate HOLDING register value to the internal modbus table of values.

in	OfsAdr	word		register address (1-9999)
in	VAL	word		value to write
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table

MODBUS_SET_HOLDINGS

Writes the appropriate HOLDINGS value to the internal modbus table of values. In the range OfsAddrStart to OfsAddrEnd.

in	OfsAddrStart	word		address start (1-9999)
in	OfsAddrStop	word		address stop(1-9999)
in	VAL	word		value to write
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table

MODBUS_SET_HOLDINGS_ALL

Write all HOLDINGS value cross all registers 1 - 9999.

in	VAL	word		value to write
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table

MODBUS_SET2_HOLDING

Writes the two appropriate HOLDING registers value to the internal modbus table of values (lower register with higher weight).

in	OfsAdr	word		register address (1-9999)
in	VAL	dword		value to write
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table

MODBUS_SET_INPUT

Writes the appropriate INPUT register value to the internal modbus table of values.

in	OfsAdr	word		register address (1-9999)
in	VAL	word		value to write
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table

MODBUS_SET_INPUTS

Writes the appropriate INPUTS value to the internal modbus table of values. In the range OfsAddrStart to OfsAddrEnd.

in	OfsAddrStart	word		address start (1-9999)
in	OfsAddrStop	word		address stop (1-9999)
in	VAL	word		value to write
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table

MODBUS_SET_INPUTS_ALL

Write all INPUTS value cross all registers 1 - 9999.

in	VAL	word		value to write
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table

MODBUS_SET2_INPUT

Writes the two appropriate INPUT registers value to the internal modbus table of values (lower register with higher weight).

in	OfsAdr	word		register address (1-9999)
in	VAL	word		value to write
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table

MODBUS_TCP_SLAVE

This function block starts listening TCP MODBUS slave deamon on the appropriate port.

in	Port	int		Listening TCP port (default: 502)
in	UnitID	byte		device bus address (1-247) (default: 1)
out	ERR	bool		F = No error, T = occur any error
out	ERR_ID	word		Error ID - see Error table