PLX3x Series ♦ Multi-Protocol Gateways
MBS Protocol
User Manual
ProSoft Technology, Inc.
Page 117 of 215
January 25, 2018
Type
Specifications
Modbus Function
Codes
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(Write) Multiple Coils
16: Force (Write) Multiple Register
22: Mask Write Holding Register (Slave Only)
23: Read/Write Holding Registers (Slave Only)
Modbus Master
Command List
Up to 100 command per Master port, each fully configurable for function,
slave address, register to/from addressing and word/bit count
Status Data
Error codes available on an individual command basis. In addition, a
slave status list is maintained per active Modbus Master port.
Polling of command list Configurable polling of command list, including continuous and on change
of data
Modbus Slave
Node address
1 to 247 (software selectable)
Status Data
Error codes, counters and port status available per configured slave port
starting at register 4400.
7.1.3 MBS Internal Database
The internal database is central to the functionality of the PLX3x gateway. The
gateway shares this database between all the communications ports on the
gateway and uses it as a conduit to pass information from one protocol to
another device on one network to one or more devices on another network. This
permits data from devices on one communication port to be accessed and
controlled by devices on another communication port.
In addition to data from the client and server, you can map status and error
information generated by the gateway into the user data area of the internal
database. The internal database is divided into two areas:
Upper memory for the module status data area. This is where the module
writes internal status data for the protocols supported by the module.
Lower memory for the user data area. This is where incoming data from
external devices is stored and accessed.
