Siemens 500 NIM - Manual (Page 49)

Installation 3-14 SIMATIC TIWAY I Series 500 NIM User Manual
3.5 Series 500 NIM Self Tests
The three levels of Series 500 NIM self tests available in the NIM are
described in the following paragraphs. They are:
•
Power-Up Self-Test
•
Run-Time Self-Test
•
User-Initiated Self-Test
The Series 500 executes a Power Up Self-Test in the following cases:
•
Immediately following the application of +5VDC from the I/O base
(power-up) as part of its initialization
•
Any time the Reset switch is pressed (See Figure 3-3)
•
Following a Disconnect Secondary command from the host
The Power-Up Self-Test exercises the processor, performs a test of on-board
RAM and ROM, and performs an internal loopback test of the
communication ports. At the start of execution, all NIM indicators (LEDs)
are turned on for approximately 1 second, then all except the Test Mode
indicator are turned off for approximately 5 seconds.
If the Power-Up Self-Test is successful, the NIM GOOD LED will be on, and
an attempt to establish communication with a Series 500 controller will be
made. If this is successful, the PC/NIM COMM GOOD LED will illuminate
and the NIM is ready for normal network operation.
Failure of the Power-Up Self-Test will cause the Test Mode LED to remain
on, and the NIM will not respond to any commmunications attempts.
If the Series 500 controller does not respond, the PC/NIM COMM GOOD
LED will remain extinguished, and the NIM will issue an Exception
Response with Error Code 1A (communication not established with attached
device) to any host computer initiating a controller interactive command to
this NIM.
The Series 500 NIM monitors itself continuously during normal operation,
as follows:
•
The Operating System continuously performs a ROM integrity test as a
background operation.
•
The NIM periodically verifies that it is capable of communicating with
the Series 500 Sequencer.
•
A Watchdog Timer circuit in the NIM helps to guard against software
lockup.
Power-up Self-Test
Run-Time Self-Test