PLX3x Series ♦ Multi-Protocol Gateways
MBS Protocol
User Manual
ProSoft Technology, Inc.
Page 125 of 215
January 25, 2018
Parameter
Value
Description
Poll Interval 0 to 65535
Specifies the minimum interval between executions of continuous
commands, in seconds. If you enter a value of 10, the command
executes 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
rearranged. This option allows 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.
You can set
Swap Code
to rearrange the byte order of data received or
sent into an order more useful or convenient for other applications.
N
O CHANGE
(0)
- No change is made in the byte ordering (1234 = 1234)
W
ORD
S
WAP
(1)
-The words are swapped (1234=3412)
W
ORD AND
B
YTE
S
WAP
(2)
- The words are swapped, then the bytes in
each word are swapped (1234=4321)
B
YTE
S
WAP
(3)
- The bytes in each word are swapped (1234=2143)
These swap operations affect 4-byte (or 2-word) groups of data.
Therefore, you should use data swapping only when using an even
number of words, such as when 32-bit integer or floating-point data.
Node
Address
1 to 255 (0 is a
broadcast)
Specifies the node address of the Modbus slave device.
Note:
Most Modbus devices only accept addresses in the range of 1 to
247, so check with the slave device manufacturer to see if a particular
slave can use addresses 248 to 255.
If you set the value to zero (0), the gateway broadcasts the command on
the network. The Modbus protocol permits broadcast commands for
write
operations.
Do not
use node address 0 for
read
operations.
Modbus
Function
1, 2, 3, 4, 5, 6,
15, or 16
Specifies the Modbus Function Code executed by the command. These
function codes are defined in the Modbus protocol. More information on
the protocol is available from www.modbus.org (http://www.modbus.org)
or see About the Modbus Protocol (page 112).) The following function
codes are supported by the gateway.
1
- Read Coil Status
2
- Read Input Status
3
- Read Holding Registers
4
- Read Input Registers
5
- Force (Write) Single Coil
6
- Preset (Write) Single Register
15
- Force Multiple Coils
16
- Preset Multiple Registers
