PLX3x Series ♦ Multi-Protocol Gateways
MBTCP Protocol
User Manual
ProSoft Technology, Inc.
Page 97 of 215
January 25, 2018
Parameter
Description
Modbus Commands
Supported
(client and server)
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 Holding
Register
15: Force (Write) Multiple Coils
16: Preset (Write) Multiple Holding Registers
22: Mask Write Holding Register (Slave Only)
23: Read/Write Holding Registers (Slave
Only)
Configurable
Parameters:
(client and server)
Gateway IP Address
PLC Read Start Register (%MW)
PLC Write Start Register (%MW)
Number of MBAP and MBTCP servers
Gateway Modbus Read Start Address
Gateway Modbus Write Start Address
Configurable
Parameters:
(client only)
Minimum Command Delay
Response Timeout
Retry Count
Command Error Pointer
Command List
Up to 160 Modbus commands (one tag per command)
Status Data
Error codes reported individually for each command.
High-level status data available from Modbus TCP/IP client (for example
PLC)
Command List Polling
Each command can be individually enabled or disabled; write-only-on-data-
change is available
6.1.2 MBTCP 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.
