Preface
I/O Link communication alarm is sometimes reported from MTBs and End-users, and generally, it can take much time to solve the trouble. In this manual, we are analyzing actual examples, and conclude how to troubleshoot these troubles. This manual is for Service people to learn about this alarm, and to solve these troubles quickly.1. Alarm Message
When I/O Link communication fails, System Alarm is issued with one of the following messages. The message changes according to the series and edition of PMC Management Software, however, its meaning and the process of troubleshooting are common.
·
PC050
IOLINK CH1 a1b1-x1y1:x2y2
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PC050
IOLINK CH2 x1y1:a2b2-x2y2
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PC050
I/O LINK(CHn) x1:y1 x2:y2
·
PC050
NMI SLC(CHn) x1:y1 x2:y2
·
PC050
NMI SLC x1:y1
·
PC150
NMI SLC x1:y1
·
971
NMI OCCURRED IN SLC (note)
·
SLC
ERROR x1(y1) : PC050
·
SLC
ERROR x1 :
PC050
(note) This message
has the register value “x1y1”
in memory dump. Refer Chapter 1.2 ‘Register
value in “971 NMI OCCURRED IN SLC”’ for detail.
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In these messages, “CHn” (n ≥ 1) means the channel of communication failure. The messages without “CHn” means the error was detected in channel 1. The portion “a1b1”, “x1y1”, “a2b2” and “x2y2” are the register values of SLC, which is I/O Link communication controller LSI. The value “a1b1” and “x1y1” are of channel 1; “a2b2” and “x2y2” are of channel 2. The register value of channel 2 will always be displayed at PMC software that supports “I/O Link expansion” option, whether the option is purchased or not. Some messages have “a1b1” and “a2b2”, which are earlier value than “x1y1” and “x2y2”.
earlier
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later
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Channel
1
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a1b1
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x1y1
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Channel
2
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a2b2
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x2y2
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The
register values are clues certainly, however, they may not be enough evidence
to find out the cause of troubles because of following reasons:
·
These
values are not the values at the instant when the first communication error was
detected, but are the values when the communication disconnected finally. This means that the values may not reflect
the direct cause, and can reflect its side effect.
·
In
case of hardware malfunction or electric noises, the register value may become
improper value.
·
The
same causes may show different register value depending on the timing of error.
Therefore, it is important to
analyze not only register value, but also the situation how the alarm occurred.
1.1SLC’s register value
1.1.1 Detail of a1, a2, x1 and x2
xn#7
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xn#6
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xn#5
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xn#4
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xn#3
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xn#2
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xn#1
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xn#0
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xn#0
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Bad data was received: If xn#1
is 1, xn#0 will always
be 1. So check xn#1
first.
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xn#1
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Slave device detected an error.
See yn for
more detail.
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xn#2
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Slave did not respond.
Link was disconnected.
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xn#3
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SLC, I/O Link controller LSI, detected parity error of internal
RAM. Exchange PMC control module, or
the board with I/O Link connector.
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xn#4
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Parity error in I/O RAM was detected. Exchange PMC control module, or the board
with I/O Link connector.
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xn#5~7
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Meaningless
1.1.1 Detail of b1, b2, y1 and y2
When slave
detected communication error (in case xn#1
is 1), this value shows the slave number and the detail of the error.
Otherwise (in
case xn#1 is 0), this byte
will be the slave number of which master communicated last, or of which master
was trying to communicate. But this
slave number does not mean the very slave with problem. For example, in case that connection between
1st slave and 2nd slave was cut when master was trying to
communicate with 3rd slave, this byte will show the number for 3rd
slave.
1.2 Register value in “971 NMI OCCURRED IN SLC”
In some CNC and PMC model, the
following screen is displayed at I/O Link communication failure. In this screen, the SLC’s register value is
not shown in the error message itself, however, you can pick up the value from
following dump display.
1.2.1 Dump with register names・ Models
・ Position of SLC’s register (bold and underlined)1.2.2 Dump without register names・ Models
・ Position of SLC’s register (bold and underlined)2 Cause of communication failure
I/O Link communication failure can
be caused by various causes such as followings:
(a) Wrong
communication cable, disconnection, unstable connection
The electric cables used for I/O
Link connection can be distinguished into the types below. Check cables are properly used. Check wiring of cables with “CONNECTING
MANUAL”. Wiring of twisted-pair needs special care: SIN must be paired with
*SIN, and SOUT with *SOUT. If wrong
signals are paired, the cable may easily affected by electric noises. Do not wire unused terminal: There are power
lines such as +24V and +5V, and unintended wiring of these lines may cause
malfunction of devices.
·
K1X : connects groups.
·
K2X : connects bases.
·
K3X : connects Optical I/O Link
Adapter or I/O Link Dummy Unit.
·
(no
name?) : connects I/O Link Signal
Divider.
(b) Wrong
connector
I/O Link
connection between groups starts from “JD1A” and ends to “JD1B”. Check the connector’s name.
(c) Loose
connection
Check all
connectors are firmly plugged. Just
plugging again sometimes solves troubles.
(d) I/O
assignment data mismatch
Mismatch
between I/O assignment data and actual I/O device configuration may cause
communication failure. For example,
combination of assignment data with “base expansion” and actual I/O
configuration without expanded base will cause System Alarm at start.
(e) Electric
noises
Refer “CONNECTING
MANUAL (Hardware)”, and take measures to avoid influence of noises.
If
communication cable and power cable are tied together, noises from power cable
may affect communication. They should be
tied separately. Shield of a
communication cable must be grounded via cable clamp. (See “CONNECTING MANUAL (Hardware)”) via cable
clamp. (See “CONNECTING MANUAL
(Hardware)”)
(a) Short
circuit of DO
With some model
of I/O module for operator's panel, short circuit of DO with ground or other DO
by wrong wiring or malfunction of some device, may cause communication failure.
(b) Insufficient
power supply or low voltage
Check the
capacity of power supply. Even if the
power supply had enough capacity at first design, later modification may need
more capacity. In some cases, we had no
trouble at power supply capacity in usual operation, but specific operation
caused low voltage.
(c) Insufficient
connection to power supply
Check the power
cable. We had several cases that the
loose connection with power supply unit disturbed stable power supply, and
caused System Alarm that occurred rarely.
(d) Malfunction
of power supply unit
Malfunction of
power supply unit may cause instant power failure and then communication
failure.
(e) Restarting
CNC without restarting slave I/O devices
I/O Link slave
devices must be restarted when I/O Link master device (CNC) is restarted. Specially, slaves of intelligent type such as
Series 0-C, Power
Mate, β amplifier, and Spindle Monitor Unit, will raise System Alarm at power
cut of master. In this situation,
restarting CNC will raise another System Alarm at CNC by bad status of slaves.
(f) System
down of slave device
When I/O Link
slave of intelligent type is connected, System Alarm at slave device will cause
System Alarm at master CNC. And System
Alarm at master CNC vice versa. In this
configuration, it is important which System Alarm occurred first, and caused
other System Alarm.
If slave device
does not raise System Alarm while master raises, this may happen by power
failure of slave device; master CNC raised System Alarm at power failure of
slave device, and then the slave device restarted.
(g) Unstable
grounding of Optical I/O Link Adapter
I/O Link
Adapter, which connects electric cable and optical cable, must be grounded to
earth via its casing.
(h) Malfunction
of CNC or I/O devices
Malfunction of
hardware is also possible. Try to change
the board with I/O Link connector such as Master PCB or PMC Board, PMC Control
Module (not detachable in some PMC model), Back Panel, each slave devices.
(i) Wrong
operation
If the System
Alarm occurred only once, it has possibility of wrong operation by human error
such as cutting power of slave device by mistake.
1 Items to check
Check the following items, judge
them totally, and find the cause such as ones in previous section.
(1) How
long did it work?
“Did
it work normally before?”
If a machine
that worked without problem suddenly started raising alarm, modification of the
machine or related facilities may be the cause; the modification may generate
electric noise, insufficient connection, short of power supply capacity. Malfunction of some device can also be the
cause.
On the other
hand, at trouble on a machine in assembling, you have to start with I/O Link
assignment data and hardware connection.
(2) Device
configuration and I/O Link assignment
“What
configuration?”
Check the
actual I/O Link configuration and assignment data; what kind of slave devices,
how they are connected with master.
And check
whether the contents of I/O Link assignment data match the actual
configuration, whether the number of I/O signals does not exceed the
specification of I/O Link, whether necessary terminator is correctly attached,
and so on, referring “CONNECTING MANUAL (Hardware)”.
(3) Timing
“What
was the machine doing?”
If System Alarm
occurs at power-on phase, check if cables connect correct pair of connectors,
and I/O Link assignment data first. If
the assignment data has entry for base expansion while the base is not attached
actually, System Alarm occurs at power-on.
When the master
CNC restarts, all slave devices must also restart. Check the power for slave devices is surely
cut when the power for master CNC is cut.
If System Alarm
occurs every time when some specific action is taken, the action can be the
cause of unstable connection, electric noises, short of power supply capacity,
or unexpected voltage by short circuit of DO.
(4) Operation
“Does
same operation always lead to same result?”
In case that
same operation always produces same System Alarm, you can find out the origin
of trouble by removing slave device one by one starting from the one of largest
group number. Removing slave device,
however, is dangerous in some cases and should be done carefully enough,
because it may bring trouble at operating the machine; such as removing I/O
device that is connected to operator’s panel.
If System Alarm
is hard to reproduce, and occurs rarely, it will be very difficult to find out
the cause of trouble. Try every
countermeasure at once, then wait and see how things turn out; changing
hardware such as master, slave and cable stuff, use power supply of more
capacity, or use another power supply additionally, enhance grounding to earth
and shield of cables, tying cables of different kind separately, and so on.
(5) Information
at System Alarm
“Does
System Alarm always provide the same information?”
Every time
System Alarm occurs, the message of System Alarm including SLC’s register
values, LED indicator of slave devices, and the message of System Alarm at
slave if occurred, should be noted and checked.
As described in former section, these may change every time System Alarm
occurs, in some cases. If these actually
change, the information from them is not so reliable.
(6) Alarm
history / System Alarm history
“Is
there any other alarm?”
Other alarm may
occur just before System Alarm of I/O Link communication, and may cause the
System Alarm. Check the Alarm history
and System Alarm history.
If slave
devices also have such histories, check them, too.
(7) SLC’s
register value
“What
information is reported from SLC?”
If all System
Alarm messages show the same SLC’s register value, the value can be an
efficient clue to the cause of trouble.
But as described before, this value is not 100% reliable. From our experiences, the value other than “n3:4m”
is not meaningful, where n and m are any hexadecimal numbers.
(8) Retry
counter
“Is
the communication stable?”
I/O Link makes
an attempt to recover communication at communication error. When it fails to recover it, it raises System
Alarm.
When I/O Link
retries communication, counter register below is incremented by one. This counter register is allocated at same
address regardless of PMC model.
By watching
this counter register, you can know whether the communication is not stable, or
the communication is generally stable but sudden error may be detected.
If
communication error occurs intermittently, and this counter is incremented
frequently, this counter can be an indicator to find out the cause; when you
exchange some hardware, and then this counter stops, you can conclude that the
exchanged hardware is the cause.
This counter
register is volatile memory. It will be
cleared at every power-on.
2 Examples2.1 System Alarm occurs about once a day.1.1 System Alarm occurs two or three times per day.1.1 System Alarm occurred at power-on after loading Ladder program at BOOT screenIn this case, CNC can not start up. To avoid System Alarm and let CNC start up, you can start it with I/O Link cable disconnected, or at BOOT screen, you can remove Ladder program or load correct Ladder program. To check the I/O Link assignment data, you need Edit function on CNC, or you need to transfer Ladder to Programmer software such as FAPT LADDER-III.
1.1 System Alarm sometimes occurs at action of conveyer after machining.1.2 System Alarm occurs at almost every automatic execution.1.3 System Alarm occurs at cycle start.1.4 System Alarm occurs at activation of conveyer system about once in five times.1.5 System Alarm occurs at displaying external alarm message.1.6 System Alarm occurs occasionally.1.7 System Alarm occurs occasionally.unknown 1.8 System Alarm occurs sometimes at power-on.unknown 1.9 System Alarm occurred after loading macro file at BOOT screen.unknown 1.10 System Alarm occurs at power-on.1.11 System Alarm began to occur on a machine that had worked for a year.unknown 1.12 System Alarm occurs at power-on.
1.2 System
Alarm occurs at “Restart I/O Link” after storing Ladder program by online
function of FAPT LADDER-II/III.
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