HEIDENHAIN TNC 407 (243 020) Service Manual - Manual (Page 96)

31-O
SERVICE MANUAL TNC
Issue:
01.09.1995
Page
80
17.2 Checking the PLC Inputs and Outputs
Two test units are available to check the inputs and outputs of the PLC:
PLC Test Unit for X41, X42 and X46
PL Test Adaptor for the PL board
With the PLC Test Unit all inputs and outputs of a connector are displayed simultaneously and all voltages can
be measured. If you use the PL Test Adaptor, only the inputs/outputs of one terminal strip of the PL board are
displayed. In this case the voltages can be measured directly at the terminals.
17.2.1
PLC Inputs
Check the PLC inputs as follows:
Connect the test unit between LE and PLC or between LE and PL.
Set the TNC as follows:
Press key Function
Switch TNC to operating mode EDITING
on
Prepare TNC for code number input
Enter code number, acknowledge with ENT
Soft key to display the tables
Soft key to display the input table
Now the logic states of the inputs are displayed on the screen. The states of the screen display must
correspond to those of the test unit. If there is a difference, measure the voltage level (see section 17.1) of
this input at the test unit. If the input voltage is correct, the input board is probably defective to and
to 1152 of PLC and graphics board, to 11’26 of PLC board).
switch TNC back to operating
NOTE:
Always switch off the main switch before engaging or disengaging any connector.