Switching Amplifier test circuit

TURCK MC13-8B Switching Amplifier test circuit

Dear Friends,
I have a TURCK MC13-8B Switching Amplifier (8channel) (catalog : www.promautomatika.ru/cont/product/turck/pdf/0599.pdf page:3). now this module don't work correctly. how can I test it to find the problem? the status LED blink constantly. I don't know how can I give input to it and test the output also can't find complete datasheet or service sheet of it.

after reviewing the circuit and brief datasheet now I know a few information about the module. it is a isolating switching amplifier and is useful for amplifying output of proximity sensors (NAMUR standard) or mechanical contacts in the automation system of industries.
the module have two main part. the left side of board is for input channels and have pullup resistors, two op-amp(LM224), a MUX(4052), a PIC MCU(16C711) that give address to MUX for choosing the input channel, a 8v Regulator, and a few DIP switches for jumper settings. the right side have a supply, a CAN interface IC(PCA82C250), a PIC MCU(16C711), CAN controller chip(intel AN82527), a mosfet(IRFD24) and driver of it(UC3715), two latch IC(74HC573), LEDs for displaying of channels. also there is a special coil and two opto-coupler between this two part of module.
I think that the operation of circuit is like this (according to datasheet and my tests):
A constant voltage of typically 8.2 VDC is applied to the terminals of an input circuit. A source impedance or internal resistor (Ri, typ. 1 k?) senses the current flow passing through the sensor at that voltage. When the proximity sensor per EN 60947-5-6 (NAMUR) is damped, the current flow in the input circuit changes. The current differential from the undamped to the damped state is used to trigger the amplifier at a defined switching point and, thus, the analogue signal is converted into a digital signal.

now I know input of this module completely but don't know output of it. why it use CAN protocol's chip and interface ?
when I give supply voltage about 15v and connect a input circuit(shunt resistor to simulate proximity sensor according to catalog)to the input channel, the module don't give 8v supply to my input circuit and thus can't detect input, thus the status LED blink constantly. do you think that this module have a enable circuit for inputs?