FANUC I/O Unit A Maintenance Manual

Counter not counting: Check if the CE (count enable) position is set to 1 and if the CSP external input is closed (stop counting when closed).

5.2 Temperature input module

ATI04A (Thermistor): Supports Pt100 or JPt100, three wire system, measurement range -50.0~300.0 ℃, resolution 0.1 ℃, accuracy ± 1% FS.

ATI04B (thermocouple): Supports K-type or J-type, with a measurement range of 0.0~600.0 ℃ and a resolution of 0.1 ℃. Need to cooperate with terminal unit ATB01B (including cold end compensation components).

Working mode:

2-channel mode: only CH1 and CH2, updated every 0.3 seconds.

4-channel automatic mode: 4-channel cyclic sampling, with a period of 0.5-10 seconds (written in units of 0.1 seconds, DO00~DO15).

4-channel manual mode: Sampling is controlled through READ requests and channel selection bits (CH SEL).

PMC interface: occupying 4 bytes for output (used for control words and cycle settings) and 4 bytes for input (status+temperature data). The temperature value is the actual temperature multiplied by 10 (binary). Abnormal detection: Disconnection, over range, cold end abnormalities, etc. are reflected through status bits DI13/DI29.

Expansion and Fiber Optic Communication

When the length of K1X cable exceeds 10 meters (or crosses cabinets and has poor grounding or strong noise environment), an optical adapter must be used instead.

I/O Link Optical Adapter: Standard Type A13B-0154-B001 (up to 200m, up to 5 cascaded levels), High Speed Type A13B-0154-B004 (100m, up to 16 cascaded levels). Cannot be mixed.

I/O Link i Optical Adapter: A13B-0154-B101, supports normal mode (200m, level 5) and high-speed mode (100m, level 10). I/O Unit-A does not support high-speed mode.

Precautions for using optical cables:

The bending radius and tension limit of optical cables are prohibited from being used in movable parts.

Keep the connector clean and wipe it with alcohol.

Fiber optic cable splicing adapter A02B-0094-K841 can be used for relay (up to 1 relay point, high-speed type not available).

Multi channel expansion:

2-channel adapter A20B-1007-0680: Split CNC's JD441/JD51A into two independent I/O links.

3-channel adapter A20B-1008-0360: splits into three channels (channel 3 only supports I/O Link, not I/O Link i). When wiring, pay attention to the total length of the cable (LA+LB) being ≤ 10m (≤ 15m inside the same cabinet).

Quick Diagnostic Checklist for LED Indicator Light Malfunctions

7.1 Interface module LED

Meaning and Handling of Module LED Status

AIF01A/A2 PWR is out of 24V without power supply or the fuse is blown. Check the power supply and replace the fuse (3.2A)

LINK power on sequence error, cable disconnection, or main station failure to communicate. Power on again according to the specifications and check the K1X cable

LINK lights up and then goes out. Slave station loses power or I/O allocation is incorrect. Check if the expansion base exists but has not been assigned

AIF01B is the same as AIF01A - but when LINK is turned off, it is necessary to check the LINK of the previous AIF01A in the same group

AIF02C LNK-1/LNK-2 shutdown corresponds to I/O Unit-A or Unit-B link failure. Check the cable and terminal resistance settings

The ER indicator light combination flashing refers to Table 2.3.4 of the manual, such as "Basic Unit Received Data Counting Error", which is commonly found in repeated or missing terminal resistors of the same unit number

AIF01D LINK mute/flash is specifically designed for I/O Link i. Standard mode slow flashing (0.5s) indicates communication in progress; High speed mode flash (0.25s) indicates communication interruption or watchdog alarm

FUSE lights up and the fuse is blown. Replace 3.2A (A60L-0001-0290 # LM32)

ALM flash (1:1): There is a disconnection between this group and the subsequent group

ALM flash (3:1) followed by instantaneous drop of power supply in the secondary group

AIF01E/E2 BA0 lights up and is communicating with the expansion base (only valid under I/O Link). Can be used to determine the location of communication faults

7.2 I/O module LED

Input module (16 points and below): A0~A7, B0~B7 correspond to the input point status. The green light indicates that the input is ON.

Output module: The same LED indicates the output status. For modules with fuse indication (such as AOD08C, AOD08D, AOA05E, etc.), the F light on indicates that the corresponding common fuse has been blown.

Output modules with protection functions (AOD08DP, AOD16DP, AOD16DM, etc.): If the F light is on, it indicates overheating or overcurrent protection triggering, not a fuse issue. Need to investigate load short circuit or overload.

Common troubleshooting process

8.1 The entire group cannot communicate, LINK does not light up

Check the interface module PWR light: if it is off, test the 24V power supply and fuse.

Confirm the power on sequence: Power on I/O Unit-A first, and then power on CNC.

Check if the K1X cable (JD1A-JD1B) is open or short circuited, and if the polarity of the twisted pair is correct (SIN/SIN, OUT/OUT).

Use the CNC side diagnostic function to see which groups have been identified. If all previous groups in this group are normal but this group is not lit, then the interface module or cable in this group is faulty.