DESCRIPTION AND OPERATION
SECURITY FUNCTIONS
I-E96-209A
2 - 3
Digital Inputs/Outputs
There are eight digital inputs and eight digital outputs
on-board. The inputs are jumper-selectable to be energized by
24 VDC, 125 VDC or 120 VAC. The inputs are optically-iso-
lated; outputs are optically-isolated open-collector type. The I/
O signals are routed to the NTDI01/NTDO02 TU or the
NIDI01/NIDO01 TM through the NKTU01, NKTM01, or
NKTU02 cable connection on the P3 card edge connector.
SECURITY FUNCTIONS
Two types of security functions are performed: module security
and control input security. Module security is provided by a
Machine Fault Timer (MFT) that is periodically reset by the
microprocessor. If, for whatever reason, the timer is not reset,
it shuts the module down, turns the front panel status LED
red, de-energizes the digital outputs and prevents the NVRAM
from being erased or written to. Control input security is pro-
vided by adding Function Code 31 (TEST QUALITY) to the con-
figuration. Each function block assigned Function Code 31 can
test the quality of up to four inputs. If the inputs are good, the
output of the TEST QUALITY block is set to Logic 0. If any of
the inputs are bad, the output of the block is set to Logic 1.
Logic within the configuration can initiate the necessary
alarms or appropriate actions.
Additionally, on-line tests are performed to verify proper hard-
ware operation. If any of these tests fail, the timer is not reset
and status LED turns red. NVRAM errors are handled differ-
ently since the module executes from a copy of the configura-
tion located in RAM. If an NVRAM checksum error is detected,
the module continues operating; however, the status LED
flashes green. After resetting the module, it will enter the error
mode.
CONFIGURATION
A configuration must be defined to determine the operations an
LMM performs on its input signals. This section explains the
function codes that can be used with an LMM. Function codes
are software algorithms that can be configured to define spe-
cific tasks. A function block in memory has a reference number
(block address) that can be used as an input reference by other
function blocks. The LMM processes defined function blocks in
ascending order.
NOTE: This instruction contains function codes specific to the
IMLMM02 only. The function codes defined in this section reflect the
function codes that were available at the time the instruction was
created. Refer to the latest
Function Code Application Manual for
additional function codes.
