Data Block Function - Mitsubishi Electric MELSEC iQ-R User Manual

1.3

Data Block Function

This function reads and writes property values using a program.
Data block is an area for each function in the buffer memory.
The following figure shows how to read the property values of an AnalogInput (instance number: 2) in a BACnet device
(instance number: 10) from a BACnet module.
Programmable controller system
Request to start reading
CONTROL: 0→1
Read target
Device instance number: 10
Object type number: 0(AnalogInput)
Object instance number: 2
PropertyIdentifier: 85(PresentValue)
*1: A programmable controller system reads property values in another BACnet device.
*2: An access block for reading is an area prepared for storing a request to start reading from another BACnet device or the information of a read target.
*3: AnalogInput object is an object to read analog values in a BACnet device to a programmable controller system.
(1) Connect a personal computer to a BACnet module, and register a data block for reading (access block for reading) to the BACnet module using a
configuration function.
(2) The data block (access block for reading) is assigned to the data assignment area in the buffer memory of the BACnet module.
(3) Write a read target and a request to start reading (CONTROL: 0 to 1) using the program of a CPU module.
(4) The values in the buffer memory of the BACnet module are applied to the data block (access block for reading) in the internal memory.
(5) The target property values are read from the read target BACnet device.
(6) The read result is sent to the buffer memory from the internal memory.
An operation example using data blocks is described in the following manual.
When reading/writing the values of properties using a program, refer to the following manual.
MELSEC iQ-R BACnet Module User's Manual (Startup)
1 FUNCTIONS
122
1.3 Data Block Function
Personal computer
(1)
*1
RCPU
(3)
Configuration function
BACnet module
Buffer memory Internal memory
(2)
Access block for Access block for
reading reading
*2 *2
0→1 0→1
10 10
2 2
(4)
85 85
54321 54321
(6)
BACnet device
(Device instance number: 10)
AnalogInput object
*3
(Instance number: 2)
Property value
PresentValue
54321
(5)