PLX30 Series
MBS Protocol
Ethernet and Serial Gateways
User Manual
ProSoft Technology, Inc.
Page 131 of 200
September 19, 2012
7.2.2 MBS Port [x] Commands
The Modbus Port[x] Commands (where x can be 1, 2, 3 or 4) sections of the PCB
tree Window are used to define a Master serial port
Command List
. This list
holds the parameters needed to poll slave devices attached to a Master port.
Parameter
Value
Description
Enable
Disabled
Continuous
Event
Command
Conditional
Specifiesif the command is to be executed and under what
conditions.
Disabled (0
)
- the command is disabled and will not be executed in
the normal polling sequence. However, the command can still be
activated using Command Control.
Continuous (1)- the command will be executed upon each scan of
the Command List if the Poll Interval is set to zero (0). If the
Poll
Interval
is set to a non-zero value, the command will be
executedwhen the interval timer for that command expires.
Event Command (2)- the command will execute only if the internal
data associated with the command changes. This parameter is valid
only for write commands(FC 5, 6, 15, and 16).
Conditional (3)
- the command will execute only if the internal bit
data associated with the command changes. It will also clear the bit
or bits in the internal database after the write command is built. This
parameter is valid only for bit-level write commands (FC 5 and 15).
Internal
Address
0 to 3999(for
register-
level
addressing)
or
0 to
63999(for
bit-level
addressing)
Specifies the database address in the gateway's internal database
to use as the destination for data brought in by a read command, or
as the source for data to be sent out by a write command. The
database address is interpreted as a bit address or a 16-bit register
(word) address, depending on the Modbus Function Code used in
the command.
For Modbus functions 1, 2, 5, and 15, this parameter is interpreted
as a bit-level address.
For Modbus functions 3, 4, 6, and 16, this parameter is interpreted
as a register-level address.
Poll Interval
0 to 65535
Specifies the minimum interval between executions of continuous
commands. The value is in seconds. Therefore, if a value of 10 is
entered, the command will execute no more frequently than once
every 10 seconds.
Reg Count
1 to 125
(for
registers)
or
1 to 800
(for
coils)
Specifies the number of 16-bit registers or binary bits to be
transferred by the command.
Modbus functions 5 and 6 ignore this field as they apply only to a
single data point.
For Modbus functions 1, 2, and 15, this parameter sets the number
of bits (inputs or coils) to be transferred by the command.
For Modbus functions 3, 4, and 16, this parameter sets the number
of registers to be transferred by the command.
Swap Code
No Change
Word Swap
Word and
Byte Swap
Byte Swap
Specifies if and how the order of bytes in data received or sent is to
be rearranged. This option exists to allow for the fact that different
manufacturers store and transmit multi-byte data in different
combinations. This parameter is helpful when dealing with floating-
point or other multi-byte values, as there is no one standard method
of storing these data types. The parameter can be set to rearrange
the byte order of data received or sent into an order more useful or
convenient for other applications.
No change(0)
- No change is made in the byte ordering (1234 =
