1034
Network Instructions Section 3-25
■ Auxiliary Area Bits and Words Used when Automatically Allocating
Communications Ports
Note 1. Use the following flowchart to determine whether to use the Network Com-
munications Port Allocation Enabled Flag (A20215) and the Network Com-
munications Completion Code Storage Address (A216 and A217).
Address Bits Name Description
A202 15 Network Communications Port
Allocation Enabled Flag
ON when there is a communications port available for automatic
allocation. This flag can be used to confirm if all eight communica-
tions ports have already been allocated before executing communi-
cations instructions.
A214 00 to 07 First Cycle Flags after Network
Communications Finished
Each flag will turn ON for just one cycle after communications have
been completed. Bits 00 to 07 correspond to ports 0 to 7. Use the
Used Communications Port Number stored in A218 to determine
which flag to access.
Note: These flags are not effective until the next cycle after the
communications instruction is executed. Delay accessing
them for at least one cycle.
08 to 15 Do not use.
A215 00 to 07 First Cycle Flags after Network
Communications Error
Each flag will turn ON for just one cycle after a communications
error occurs. Bits 00 to 07 correspond to ports 0 to 7. Use the Used
Communications Port Number stored in A218 to determine which
flag to access.
Note: These flags are not effective until the next cycle after the
communications instruction is executed. Delay accessing
them for at least one cycle.
08 to 15 Do not use.
A216
and
A217
--- Network Communications
Completion Code Storage
Address
The completion code for a communications instruction is automati-
cally stored at the address with the I/O memory address given in
these words. Place this address into an index register and use indi-
rect addressing through the index register to reach the communica-
tions completion code.
A218 --- Used Communications Port
Number
When a communications instruction is executed, the number of the
communications port that was used is stored in this word. Values
0000 to 0007 hex correspond to communications ports 0 to 7.
YES
NO
NO
YES
Use A20215 and perform exclu-
sive control.
Using more than 8 com-
munications ports?
Communications comple-
tion codes required?
Use A216 and A217 with indirect
addressing via an index register to
check the code.
Use automatic communications
port allocation.
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