3 DETAILS OF FUNCTION
3.2 MELSEC Data Link Functions
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mdRandREx
This function reads devices randomly.
■
Format
long mdRandREx(long lPath, long lNetNo, long lStNo, long* plDev, short* psBuf, long lBufSize)
■
Argument
The specification method of the randomly selected device (plDev) is as follows:
■
Description
• This function reads devices specified to the randomly selected device (plDev) from a module specified to the network
number (lNetNo) and the station number (lStNo).
• The read data is stored in the read data storage destination (psBuf) in word units in order of the specification to the
randomly selected device (plDev). A bit device is stored per 16 points, a word device is stored per 1 point, and a double-
word device is stored in word units.
• Specify so that the total number of read points specified for each block is 10240 points or less. Otherwise, a size error (-5)
occurs.
• Communication time varies significantly depending on the contents specified to the randomly selected device (plDev).
To reduce communication time, use the mdReceiveEx function.
• To access the own station, set the station number to 255. When the actual station number is used, an error will occur.
Argument
Name
Description
IN/OUT
lPath
Path of channel
Specify the path of the opened channel.
IN
lNetNo
Network number
Specify the network number of target module.
IN
lStNo
Station number
Specify the station number of target module.
IN
plDev
Randomly selected device
Specify the number of blocks, device type, start device number, and device points of
devices to be read.
IN
psBuf
Read data storage destination
Specify the storage destination (address) of read data.
OUT
lBufSize
Read data storage destination
size
Specify the area size reserved in the read data storage destination in byte units.
IN
plDev
Description
plDev[0]
Number of blocks
plDev[1]
Device type
Block 1
plDev[2]
Start device number
plDev[3]
Number of read points
plDev[4]
Device type
Block 2
plDev[5]
Start device number
plDev[6]
Number of read points
plDevLst[3n+1]
Device type
Block n
plDevLst[3n+2]
Start device number
plDevLst[3n+3]
Number of read points
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