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Modbus TCP/IP Driver Manual
Page 19 of 23
Appendix A.5. Reading Device Identification
Appendix A.5.1. Client Side Map Descriptor
There could be various objects describing device identification.
Each object has its own ID (0-255). Only the first 7 ID’s (0-6) objects are defined and are ASCII Strings.
Object ID
Object Name
0
VendorName
1
ProductCode
2
MajorMinorRevision
3
VendorUrl
4
ProductName
5
ModelName
6
UserApplicationName
The Client Side Map Descriptors read the specified object from a remote device. They will store the object
data character-by-character in the specified data array, up to the limit specified by the Map Descriptor
length.
Any object could have up to 248 characters.
//Client Side Map Descriptors
Map_Descriptors
Map_Descriptor_Name
, Data_Array_Name
, Data_Array_Offset
, Function
, Node_Name
, Address
, Length
CMD_Vendor_name
, DA_Vendor
, 0
, Server
, PLC_01
, 0
, 248
CMD_Product_code
, DA_Prodcode
, 0
, Server
, PLC_01
, 1
, 248
Appendix A.5.2. Server Side Map Descriptor
Server Side Map Descriptors can define any object as shown below:
The Driver will serve strings from the data array as an object value.
The string from the data array is considered complete if the character is 0 (null) or if all characters are
fetched as per the Map Descriptor length.
If the first character is 0 (null) then the single character '-' will be used as the object value.
//Server Side Map Descriptors
Map_Descriptors
Map_Descriptor_Name
, Data_Array_Name
, Data_Array_Offset
, Function
, Node_Name
, Address
, Length
CMD_Vendor_name
, DA_Vendor
, 0
, Server
, PLC_01
, 0
, 248
CMD_Product_code
, DA_Prodcode
, 0
, Server
, PLC_01
, 1
, 248
Appendix A.6. Broadcasting Write Messages
Standard Modbus TCP/IP node addresses range from 1 to 254, with 0 being reserved for broadcast
messages. Setting the Node ID to 0 allows write messages to be broadcast to all configured slave
devices.
To perform a valid broadcast, the node ID will need to be set to 0 and the map-descriptor function will
need to be set to a write.
Example
// Client Side Nodes
Nodes
Node_Name
, Node_ID
, Protocol
, Port
, Address_Type
BROADCAST_NODE
, 0
, Modbus/TCP
, R2
, PDU
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