Electrical Connections; Output Specifications - Renishaw ATOM Installation Manual

Electrical connections

Grounding and shielding
FPC readhead
FPC cable
Shield
(recommended)
For more information on FPC contact your
local Renishaw representative.
Connector/
Cable readhead
interface
Shield
IMPORTANT: The shield should be connected to the machine earth (Field Ground).
NOTE: Maximum cable length between interface and customer electronics is
25 m for ACi and Ri and 50 m for Ti
(Maximum length for ACi, Ti with 40 or 50 MHz clocked output is 25 m).
Recommended signal termination
Digital outputs
0 V
Interface
Customer
220 pF
A B Z E+ electronics
120R
Cable Z = 120R
0
A B Z E-
220 pF
0 V
Standard RS422A line receiver circuitry
Capacitors recommended for improved noise immunity
Remote CAL operation
CAL
Remote CAL operation is possible
via the CAL pin.
For applications where no interface is used,
remote of CAL operation is essential.
0 V
Analogue outputs
V V V +
0 1 2
120R
V V V -
0 1 2
ATOM
rotary installation guide

Output specifications

Analogue output signals
All ATOM readheads and
ACi/customer
Ri and Ti analogue interfaces
electronics
5 V
Incremental 2 channels V
Output
signals
0 V
(V +)-(V -)
1 1
Customer
(V +)-(V -)
2 2
electronics
5 V
Output
signals
Reference
0 V
(V +)-(V -)
0 0
Differential signals V
Set-up
(Readhead, ACi, Ri and Ti analogue)
During normal operation
3.3 V (nom)
Voltage at
X and V
X
0
0
Between 50% and 70% signal level, X and V
Time spent at 3.3 V increases with incremental signal level.
At >70% signal level V
During CAL routine
3.3 V
Voltage
at V
X
1.65 V
0 V
and V differential sinusoids in quadrature,
1 2
centred ~ 1.65 V (90° phase shifted)
40/20 µm
0.7 to 1.35 Vpp with green
LED indication (readhead)
and 120R termination.
0°
1 Vpp
45°
Bi-directionally repeatable
Differential pulse V
360° (nom) centred on 45°
(after CAL)
+ and V - centred on ~ 1.65 V
0 0
50% Signal level 70% 100%
is a duty cycle, 20 µm duration.
X
is nominal 3.3 V.
X
(Readhead, Ri analogue and Ti analogue only)
>70% signal >70% signal
Normal operation Normal operation
Incremental Reference
calibration mark
calibration
Start of End of
calibration calibration
routine End of routine
incremental
calibration
routine
Digital output signals
Form – Square wave differential line driver to EIA RS422A
All ACi interfaces and Ri and Ti digital interfaces
Incremental … 2 channels A and B in quadrature (90° phase shifted)
Signal period
Resolution
A
B
Reference …
Z
0
*
Set-up (Ti digital only)
1
Voltage
at X
0
0 Signal level
Setup signal voltage proportional to incremental signal amplitude
Alarm = Differential line driven output (Ri and Ti digital)
E
>15 ms
Interface Alarm asserted
model when
Ri0004
<40% signal
Ri0008
or
Ri0020
overspeed
Ri0040
Ri0100
<20% signal
Ri0200
or
>130% signal
Ri0400
3-state alarm (ACi, Ri and Ti digital)
Differentially transmitted signals forced open circuit for >15 ms when
alarm conditions valid.
(Ri and Ti alarm conditions as detailed above
ACi alarm conditions: <40% signal or overspeed)
*
Set-up signals as shown are not present during calibration routine
=
Inverse signals not shown for clarity
Synchronised pulse Z, duration as resolution
100%
Interface Alarm asserted
model when
Ti <20% signal
or
>135% signal
or
overspeed
32