Caen ELS PreDAC User manual

1
PreDAC
PREcision multi-channel
Digital to Analog Converter
User’s Manual
All Rights Reserved
© CAEN ELS s.r.l.
BEAMLINE ELECTRONIC INSTRUMENTATION

Rev. 1.2 –October 2014
This product is
certified.
CAEN ELS s.r.l.
Via Vetraia, 11
55049 Viareggio (LU) –Italy
Mail: [email protected]
Web: www.caenels.com

3

PreDAC User’s Manual
Table Of Contents
1. INTRODUCTION..............................................................................................10
1.1 THE PREDAC -DIGITAL TO ANALOG CONVERTER ........................................10
1.2 THE PREDAC AT A GLANCE .........................................................................11
1.3 FEATURES .....................................................................................................13
1.4 OFFSET CALIBRATION ...................................................................................13
1.5 DITHERING....................................................................................................14
2. SOFTWARE COMMANDS.............................................................................15
2.1 COMMAND SYNTAX......................................................................................15
2.2 VOLTAGE OUTPUT COMMANDS ....................................................................17
2.2.1 SET Command .........................................................................................17
2.2.2 TRG Command.........................................................................................19
2.2.3 GATE Command......................................................................................21
2.3 CONFIGURATION COMMANDS.......................................................................23
2.3.1 STATUS Command ..................................................................................23
2.3.2 MAX Command........................................................................................26
2.3.3 MIN Command.........................................................................................26
2.3.4 INTERLOCK Command...........................................................................27
2.3.5 TEMP command.......................................................................................28
2.3.6 VER Command.........................................................................................29
2.3.7 HWRESET Command ..............................................................................30
2.3.8 ID Command............................................................................................31
2.3.9 IDSET Command .....................................................................................32
2.3.10 RES Command .....................................................................................33
2.4 COMMAND TABLE SUMMARY.......................................................................34
3. ETHERNET COMMUNICATION .................................................................35
3.1 IP ADDRESS ASSIGNMENT ............................................................................35
3.2 CAENELS DEVICE MANAGER .......................................................................36
3.2.1 Searching for connected devices..............................................................36
3.2.2 Device Configuration...............................................................................38
3.2.3 Firmware Upgrade ..................................................................................39
4. I/O CONNECTORS...........................................................................................40
4.1 POWER CONNECTOR .....................................................................................40
4.2 TRIGGERS CONNECTOR.................................................................................41
4.3 INTERLOCK AND GENERAL I/O CONNECTOR..................................................41
4.4 ETHERNET AND SFP CONNECTOR .................................................................42
4.5 OUTPUT BNC CONNECTORS..........................................................................43
5. TECHNICAL SPECIFICATIONS ..................................................................44
6. MECHANICAL DIMENSIONS.......................................................................46
7. PREDAC POWER SUPPLY ............................................................................47
7.1 THE PS1112 LINEAR POWER SUPPLY ...........................................................47
7.2 THE PS1112 AT A GLANCE ...........................................................................48
7.3 I/O CONNECTORS..........................................................................................48

PreDAC User’s Manual
7.3.1 AC Line Input Connector.........................................................................48
7.3.2 AC Line Voltage Select Switch.................................................................49
7.3.3 Output Connectors...................................................................................50
7.3.4 Cabling.....................................................................................................50
7.4 TECHNICAL SPECIFICATIONS.........................................................................50
8. APPENDIX.........................................................................................................51
8.1 LIST OF THE ERROR CODES...........................................................................51

PreDAC User’s Manual
Document Revision
Date
Comment
0.1
February 14th 2014
Document created
1.0
April 10th 2014
Images and description
added
1.1
July 25th 2014
AC/DC part modified
1.2
October 29th 2014
Manual graphics changed
1.3
April 16th 2018
MAX/MIN commands,
updated error codes

PreDAC User’s Manual
Safety information - Warnings
CAEN ELS will repair or replace any product within the guarantee period if the
Guarantor declares that the product is defective due to workmanship or materials and
has not been caused by mishandling, negligence on behalf of the User, accident or any
abnormal conditions or operations.
Please read carefully the manual before operating any part of the instrument
WARNING
Do NOT open the boxes
CAEN ELS d.o.o. declines all responsibility for damages or injuries caused
by an improper use of the Modules due to negligence on behalf of the User. It is
strongly recommended to read thoroughly this User's Manual before any kind of
operation.
CAEN ELS d.o.o. reserves the right to change partially or entirely the contents of this
Manual at any time and without giving any notice.
Disposal of the Product
The product must never be dumped in the Municipal Waste. Please check your local
regulations for disposal of electronics products.

PreDAC User’s Manual
Read over the instruction manual carefully before using the instrument. The
following precautions should be strictly observed before using the PreDAC device:
WARNING
Do not use this product in any manner not
specified by the manufacturer. The protective
features of this product may be impaired if it is
used in a manner not specified in this manual.
Do not use the device if it is damaged. Before you
use the device, inspect the instrument for possible
cracks or breaks before each use.
Do not operate the device around explosives gas,
vapor or dust.
Always use the device with the cables provided.
Turn off the device before establishing any
connection.
Do not operate the device with the cover removed
or loosened.
Do not install substitute parts or perform any
unauthorized modification to the product.
Return the product to the manufacturer for service
and repair to ensure that safety features are
maintained
CAUTION
This instrument is designed for indoor use and in
area with low condensation.

PreDAC User’s Manual
The following table shows the general environmental requirements for a correct
operation of the instrument:
Environmental Conditions
Requirements
Operating Temperature
0°C to 45°C
Operating Humidity
30% to 85% RH (non-condensing)
Storage Temperature
-10°C to 60°C
Storage Humidity
5% to 90% RH (non-condensing)

PreDAC User’s Manual
10
1.Introduction
This chapter describes the general characteristics and main features of the
PreDAC Multi-channel Digital to Analog Converter.
1.1 The PreDAC - Digital to Analog Converter
The PreDAC Multi-channel Digital to Analog Converter by CAEN ELS is a (up
to) 4-channel, 21-bit resolution, wide-bandwidth Digital to Analog Converter (DAC)
which is especially designed for operation with the BEST (Beamline Enhanced
Stabilization Technology) system.
The core of the PreDAC system is formed of high-speed 16-bit digital to analog
converter that uses dithering technique and active low-pass filtering to obtain stable
high accuracy (21-bit) output signal.
This device is capable of outputing ±12 V bipolar voltage with resolution of 12
V –i.e. 21 bits of resolution on the bipolar output range. Output voltage noise is
suppressed using a 4th order active low-pass filter with cut-off frequency (-3 dB) of 10
kHz. Low temperature drifts, good linearity and very low noise levels enable users to
perform high-precision voltage signal generation.
The PreDAC is typically fitted with two output channels but can be optionally
upgraded to have three or even four output channels. It is housed in a light, robust and
extremely compact metallic box that can be placed as close as possible to the actuator
power driver in order to reduce cable lengths and minimize possible noise pick-up. It is
specially suited for applications where multi-channel simultaneous actuations are
required, a typical application being the control of position (X, Y) and intensity (I0) of
the photon beam in synchrotron radiation X-ray beamlines.
The PreDAC communication to a host PC is guaranteed by a standard 10/100/1000
Mbps Ethernet TCP/IP protocol while its integration in the BEST (Beamline Enhanced
Stabilization Technology) system is performed via the SFP link present on the rear
panel.

PreDAC User’s Manual
11
1.2 The PreDAC at a Glance
The PreDAC unit and its I/O connections can be easily seen in Figure 1(front)
and in Figure 2 (rear).
Figure 1: front view of a PreDAC unit
Figure 2: rear view of a PreDAC unit
Output Channels
ON, CL and
STATUS LEDs
Power Switch
Power
connector
Power and
Configuration
LEDs
Trigger
connectors
Interlocks and
general
input/output
connector
Reset
button
Ethernet and SFP
communication
interfaces

PreDAC User’s Manual
12
There are up to four BNC connectors for outputting the analog voltages and
various status LEDs placed on the front panel of the PreDAC unit. The total number of
BNC connectors depends on the configuration of the PreDAC unit (default: two
channels).
The two white LEDs on the front panel: the left one is the ON LED and it is
turned on when at least one of the output channels is feeding the voltage to its
corresponding connector. The other white LED is marked with CL (Closed Loop) and
can be found on the rightmost side of the front panel. When lit up is indicating that the
PreDAC is working in conjunction with the BEST system in the closed loop for beam
stabilization.
A blue STATUS LED, which is used to signal the correct operation of the
PreDAC device, is also visible from the front panel. During normal operation of the
PreDAC unit the STATUS LED is blinking with a frequency of 0.5Hz –i.e. the LED
changes its status every 2 seconds; if a fault condition arises, the LED blinks with a
higher frequency of 2 Hz (the led changes its status every 0.5 seconds). During the boot
phase of the PreDAC unit (which takes about 12 seconds after a power cycle or
hardware reset) all LEDs are turned on.
The power connector, power switch, two LEDs, LEMO connectors for I/O
triggers, interlock and general I/O connector, a standard RJ45 Ethernet connector and
an SFP connector are placed on the rear panel of the device.
The blue CFG LED indicates that the on-board FPGA is correctly configured
(in this case the LED is turned on). The green DC OK LED indicates that the internal
sections are correctly powered on.
The three coaxial LEMO connectors for I/O triggers are also placed on the rear
panel. Please note that only the IN 1 signal is enabled and can be used for a
synchronized voltage output (see the Triggers Connector section). The other two
connectors –i.e. IN 2 and OUT –are reserved for future use.
The “Interlocks and general I/O connector” has the pinout configuration shown
in Figure 3:
Figure 3: Interlock and general I/O connector
Pin #1
Pin #10

PreDAC User’s Manual
13
Pin #
Function
1-2
Reserved
3-4
Not present
5-8
General purpose I/O
9-10
External interlock
The external interlock pins can be used to detect an external event, which can
be used to trigger the external interlock fault and to switch the present voltage outputs
to a zero level (see Interlock and general I/O connector section for more information).
Please note that these interlock pins are galvanically isolated from ground.
The General purpose I/O pins are not yet used and they are reserved for future
use on the device.
On the rear panel of the PreDAC there is a small hole that gives access to a reset
button (“RST”), which can be used to reset the unit. Next to the reset button are placed
a RJ45 Ethernet connector (“ETH”), which is used to communicate with the unit and a
Small form-factor pluggable transceiver (“SFP”) which will be used for future updates.
1.3 Features
A host PC is necessary in order to operate the PreDAC unit and properly set/check
the desired parameters (e.g. output voltage).
Please refer to the Software commands chapter for a complete description of
available commands, their purposes and their syntax.
1.4 Offset calibration
The PreDAC device is already factory-calibrated during the production process.
Gain and offsets are stored in the non-volatile internal memory.
However, user can perform an additional calibration –i.e. a User Defined
Calibration –for example for nulling application specific offsets.

PreDAC User’s Manual
14
1.5 Dithering
Internal dither frequency for each channel is fixed to 100 kHz. This enables to
achieve 21 bits of resolution in the standard operation mode (the minimum step size
equals 12 V).
The noise introduced by the dithering process is suppressed with active filtering.
The fourth-order active filtering have 80 dB roll-off so the dithering noise is extensively
damped.
In addition to this standard operation mode it is also possible to have the output
voltage without the use of the dithering: the output voltage resolution is reduced to 16
bits (minimum step size equals 366 V) even if the dithering noise is not present.

PreDAC User’s Manual
15
2.Software commands
This chapter describes the software commands used for the correct
configuration of the PreDAC Digital to Analog Converter and for its data readout.
For more information about the Ethernet settings see the Ethernet
Communication chapter.
2.1 Command Syntax
The command structure and syntax used by the PreDAC protocol are described
in the following sections.
Commands must be sent in ASCII format and are composed by:
one “command field”
none, one or two “parameter field”
Please note that these fields are separated by a colon (‘:’or ‘0x3A’in
hexadecimal notation). The number of “parameter fields”depends on the specific
command.
All commands are NOT case sensitive and therefore the command string can
be sent either using uppercase or lowercase characters (conversion to uppercase
characters is performed internally).
Each instruction must be terminated with a ‘carriage return\line feed’sequence
‘\r\n’ (or ‘0x0D 0x0A’in hexadecimal notation or commonly CRLF).

PreDAC User’s Manual
16
Command Example:
RNG:1\r\n
-“RNG”is the command field;
-‘:’is the parameter’s separation character;
-‘1’is the first parameter field;
-‘\r\n’are the termination sequence of the command.
Commands are processed one at a time; therefore user must wait for a response
from the unit before sending the next command. All the responses from the PreDAC
device are in upper case and are terminated with the same ‘carriage return\line feed’
sequence (‘\r\n’) –i.e. CRLF –used in the command.
The reply from the device depends on the given command; for more information
about the single command please refer to the specific command section.
There are two specific replies that are commonly used in many commands, and
that indicate that the command has been correctly elaborated or not. These replies are
hereafter presented:
ACKnowledge (‘ACK’) indicates that the command is valid and it was correctly
elaborated by the device:
ACK\r\n
-“ACK”is the ACKnowledgement response to a valid command;
-‘\r\n’ is the termination sequence of the reply.
Not AcKnowledge (‘NAK’) indicates that the command is either not valid or that
it was not accepted by the device; the “NAK”reply is followed by an “error code”
field, which can be used to determine the cause of the error (see the List of the
Error Codes appendix for a detailed list of all possible error codes):
NAK:nn\r\n
-“NAK”is the Not AcKnowledged response to an invalid command;
-‘:’ is the parameter’s separation character;
-‘nn’is a the number of the error code;
-‘\r\n’ is the termination sequence of the reply.
The list of commands used by the PreDAC and the corresponding syntax is
hereafter presented as well as a description of each command purpose and any special
requirements related to the specific command. The commands are hereafter described
and are grouped in categories based on their purpose.

PreDAC User’s Manual
17
2.2 Voltage Output Commands
The Voltage Output commands, used in order to set output voltage on one or all
channels of the PreDAC device, are described in the following section.
2.2.1 SET Command
The PreDAC output voltage can be set by the means of SET command. Output
voltage can be set separately for each channel or on all channels at one time.
The correct format for the SET command is as follows:
SET:channel:value\r\n
where: -channel is the channel number (or all);
-value is the voltage output value (in [V]);
The channel parameter can be chosen between these values:
-“CH1” for the channel 1;
-“CH2” for the channel 2;
-“CH3” for the channel 3;
-“CH4” for the channel 4;
-“ALL” for the concurrent write of the same value to all channels.
The value parameter is defined as the output voltage to be set (in [V]). The value
field is concatenated from the following subfields:
±XX.YYYYYY
-“±”field for the number sign: “+” or “-”;
-“XX”for the tens and units of the value;
-“.” is decimal delimiter;
-“YYYYYY”for decimal places.
If more decimal places than the PreDAC resolution are sent to the unit, the value
is rounded to the closest actable one and additional places are discarded. The resolution
of the output voltage can be set with the RES command, which is described in the
section 2.3.10 RES Command.
The value field can also have two other values:
-“OFF” to set zero voltage on the selected channel/channels;
-“?” for the readback of the set voltage on the selected channel/channels.

PreDAC User’s Manual
18
Examples:
SET output voltage to 2.123456 V on all channels example:
SET:ALL:+2.123456\r\n
ACK\r\n
SET read on channel 2 example:
SET:CHN2:?\r\n
SET:CH2:-11.123456\r\n
SET zero voltage on channel 3 example:
SET:CH3:OFF\r\n
ACK\r\n

PreDAC User’s Manual
19
2.2.2 TRG Command
The TRG Command enables to synchronize the PreDAC output voltage setting
to an external event via the hardware “Trigger/Gate” signal (refer to the Triggers
Connector section). This feature is extremely useful when the digital to analog
converter must be synchronized to an external event (e.g. an experimental time window
or a machine specific frequency).
In the normal mode the execution of the SET command reflects in the
immediate change of the output voltage value. In the trigger mode, on the other hand,
the execution of the SET command does not get into operation immediately. The output
voltage value which is set with the SET commands is saved into memory (on a
temporary register): when the external signal occurs it forces the change of the output
voltage setting. The trigger mode operation is hereafter described.
As soon as the “TRG:ON\r\n”command is received the PreDAC unit replies
with an acknowledgement string (“ACK\r\n”) and enters the trigger mode. When
entering this mode, the unit waits for a rising edge (positive edge) on the corresponding
“Trigger/Gate” input signal. As soon as this event is detected by the PreDAC unit, the
internal logic transfers the output voltage value from the temporary register to the
output register which results in the output voltage update on the BNC output connectors.
This behavior is kept until the trigger mode is disabled with the “TRG:OFF\r\n”
(default) command. Please note that an acknowledgment string is sent back to the host
after a “TRG:ON\r\n”or “TRG:OFF\r\n”command is received.
User can set different output voltages on various channels with different SET
commands corresponding to voltage setting on each channel and then update them
simultaneously as soon as the external trigger pulse is received (see the example below).
Each subsequent write to the channel temporary register overwrites the previous value,
so only the last written and stored value is fed to the output register and thus to the
output connector.
To read the actual trigger mode status it is possible to use the command:
“TRG:?\r\n”. The generated reply to this command has the next form: “TRG:ON\r\n”
when the “trigger mode” is enabled or “TRG:OFF\r\n”when the trigger mode is
disabled.
Example:
TRG example:
TRG:ON\r\n
ACK\r\n
(pause)

PreDAC User’s Manual
20
SET:CH1:+2.123456\r\n
ACK\r\n
SET:CH3:+4.563578\r\n
ACK\r\n
(pause)
Trigger/Gate pin signal
(positive edge event )
Output voltage on the output
BNC connector is updated.
(pause)
TRG:OFF\r\n
ACK\r\n