Chapter 15
Instruction Set Overview
15–3
I/O Message and Communications Instructions – Chapter 18
Instruction Name
and Mnemonic
5/02
Only
•
Function - Output Instructions
Immediate Input
with Mask
IIM
When conditions preceding it in the rung are true, the
IIM instruction is enabled and interrupts the program
scan to read the status of a word of external inputs and
transfer it through a mask to the input data file.
Immediate Output
with Mask
IOM
When conditions preceding it in the rung are true, the
IOM instruction is enabled and interrupts the program
scan to read a word of data from the output data file
and transfer the data through a mask to the
corresponding external outputs.
Message
Read/Write
MSG
•
This instruction transfers data from one node to another
on the DH-485 network. When the instruction is
enabled, message transfer is pending. Actual data
transfer takes place at the end of the scan, during the
communications portion of the operating cycle.
Service
Communications
SVC
•
When conditions preceding it in the rung are true, the
SVC instruction interrupts the program scan to execute
the communications portion of the operating cycle. The
program scan time then resumes from where it left off.
I/O Interrupt Enable
I/O Interrupt Disable
Reset Pending
I/O Interrupt
IIE
IID
RPI
•
•
•
The IIE, IID, and RPI instructions are used with
specialty I/O modules capable of generating an
interrupt. See chapter 31 for functional details.
I/O Refresh
REF
•
When conditions preceding it in the rung are true, the
REF instruction interrupts the program scan to execute
the I/O scan (write outputsservice commsread inputs).
The program scan then resumes from where it left off.
