The MSTR Instruction
840 USE 115 00 Version 1.0
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3.2.2 Representation
Figure 16 MSTR Block Structure
Inputs
The MSTR instruction has two control inputs:
the input to the top node enables the instruction when it is ON
the input to the middle node terminates the active operation when it is ON
Outputs
The MSTR instruction can produce three possible outputs:
the output from the top node echoes the state of the top input - it
oes ON
while the instruction is active
the output from the middle node echoes the state of the middle input - it
oes
ON if the MSTR operation is terminated prior to completion or if an error occurs
in completin
the operation
the output from the bottom node
oes ON when an MSTR operation has been
completed successfull
all outputs are zero indicates four MSTR instructions are alread
in pro
ress
Top Node
Content
The 4
x
re
ister entered in the top node is the first of several
network dependent
holdin
re
isters that comprise the network
control block
. The control block
structure differs accordin
to the network in use. For the TCP/IP Ethernet network
the control block structure is as follows:
control
block
data
area
MSTR
len
th
Enables selected
MSTR operation
Terminates active
MSTR operation
Operation is active
Operation terminated
unsuccessfull
Operation successful
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