Watlow RMA PLUS RMAP-AA Series, User Manual

Page: 39 / 75

Version 1.0 PN: 2042-8198
Page 39 of 75 DN: 10-32813
You may also disable the Watbus discovery feature. Software tools use this feature to discover Watbus
devices on an Ethernet network. By disabling this discovery feature, you must specify the IP address or
host name to make a connection with PC software. See key
Discover .
Modbus® TCP Server
Setup keys: ModbusTcp
The RMA PLUS provides up to three (priority based) Modbus® TCP sessions. Unlike Watbus, Modbus®
TCP does not proxy requests. It interacts asynchronously with a user-defined data model loaded on
initialization and configured by way of a USBD gateway file. Because of this, there is virtually no delay
between request and response.
The keep-alive feature is enabled on all accepted sockets. This prevents socket leaks if a socket is not
closed properly. Typical causes include application hang / crash, loss of link, severed network, half close,
etc.
The RMA PLUS is a Modbus® TCP server and only implements the following Modbus® function codes:
•
3: Read Holding Registers
•
4: Read Input Registers
•
6: Write Single Register
•
16: Write Multiple Registers
Modbus® TCP supports all integer data types, floats, enums, and Watbus Parameter types. Strings are
not implemented. See
Data Types for more information.
This service is enabled by default for all model numbers. It may be disabled by writing “No” to the
Modbus TCP Enable member. NOTE: A reset is required for this change to take effect.
The 16-bit word / register order of multi-register data types may be changed to suit the client
application. By default, the word order is low, high.
Ethernet 70 (0x46), Instance 2
Member ID Member Name Data Type Access NV Min Max Default Comments / Description
3 0x03 Modbus TCP Enable ENUM16 RW F 106 59: No
106: Yes
4 0x04 Modbus TCP Word Order ENUM16 RW F 1331 1331: Low High
1330: High Low
The object model for the Modbus® TCP server is user-defined. A sample file (shown below) exists in the
path defined by the key
ModbusTCP . Add records to this file as necessary keeping the following in mind:
•
The Modbus® register is user-defined. It is an unsigned 16-bit integer with a range of 0 – 65535.
•
Records must be sorted in ascending order by Modbus® register (Column A).
•
The file may contain a maximum of 2000 valid records.
•
There is currently a maximum of 500 unique data points per Watbus bus and zone.
•
You must respect the data type of the target element, i.e. 32-bit integers, floats and parameters
consume 2 registers, so you must skip a register number before starting the next custom data point.