WaveStar Color Monitor_____________________________________________________________
Ctrl Nr: PM375103 Revision: 003
16
2.7
Communicating with the Monitor: Commands and Replies
2.7.1
Modbus Commands and Replies
Upstream Modbus on the Color Monitor supports three (3) Modbus commands only (with typical flag
and data values shown in hexadecimal) for communicating with the points lists of the Monitor or
devices in its chain:
1) Read Slave ID (command 11)
Sent Hex: 01 11 C0 2C
Reply Hex: 01 11 0D EA FE 52 50 50 20 44 69 73 70 6C 61 79 A3 A6
2) Read Multiple Holding Registers (command 3)
Sent Hex: 01 03 00 00 00 01 84 0A
Reply Hex: 01 03 02 00 00 B8 44
3) Write to a Single Register (command 6)
Sent Hex: 01 06 00 00 00 00 89 CA
Reply Hex: 01 06 00 00 00 00 89 CA
It is important to carefully verify early in system bring-up that the registers you are addressing are the
correct ones. In a points list or Modbus register map, the first analog channel is numbered 1 but is
accessed in software with an index value of 0. Consequently, it is common for a system to be one
register off. Because adjacent registers often have similar readings, being one register off is not
necessarily apparent.
Most analog values are 2-byte integers representing a measured parameter such as input voltage or
current. KWH uses two (2) adjacent 2-byte integers. Some parameters require scaling and are so
noted in the points list.
2.7.2
Limit on Open Sockets
When using Modbus TCP/IP, the Color Monitor can have at most five (5) sockets open at any one
time.
2.7.3
SNMP Commands
Only SNMP version 1 is supported.
The following commands are supported and are typical for the product:
•
snmpget
•
snmpgetnext
•
snmpset
See the MIB file for specifics. The MIB can be downloaded from the PDI website. Reference the
Bibliography in this manual.
