Schneider Optics Web Embedded Server - Manual (Page 37)

The MSTR Instruction
840 USE 115 00 Version 1.0 27
3.2.2 Representation
Figure 16 MSTR Block Structure
Inputs The MSTR instruction has two control inputs:
z
the input to the top node enables the instruction when it is ON
z the input to the middle node terminates the active operation when it is ON
Outputs The MSTR instruction can produce three possible outputs:
z the output from the top node echoes the state of the top input - it goes ON
while the instruction is active
z
the output from the middle node echoes the state of the middle input - it goes
ON if the MSTR operation is terminated prior to completion or if an error occurs
in completing the operation
z
the output from the bottom node goes ON when an MSTR operation has been
completed successfully
z all outputs are zero indicates four MSTR instructions are already in progress
Top Node
Content The 4x register entered in the top node is the first of several (network dependent)
holding registers that comprise the network control block. The control block
structure differs according to the network in use. For the TCP/IP Ethernet network
the control block structure is as follows:
control
block
data
area
MSTR
length
Enables selected
MSTR operation
Terminates active
MSTR operation
Operation is active
Operation terminated
unsuccessfully
Operation successful