Alicat EPC Series User manual

Electronic Pressure and Vacuum
Controllers
The Fastest Flow Controller Company in the World!
Operating Manual
EPCD-Series EPC-Series

2
Thank you for purchasing an E-Series Vacuum and Pressure Controller. Please take
the me to nd and read the informaon for your specic device. This manual
covers the following Alicat Scienc instruments:
EPC-Series Vacuum and Pressure Controllers
EPCD-Series Vacuum and Pressure Controllers
The installaon (plumbing, mounng and power/signal connecon instrucons
are applicable to all E-Series pressure devices.
Please contact Alicat at 1-888-290-6060 or [email protected]om if you have

06/30/2017 Rev.2 DOC-EPCMAN
Notice: Alicat Scientic, Inc. reserves the right to make any changes and improvements to the products
described in this manual at any time and without notice. This manual is copyrighted. This document may not,
in whole or in part, be copied, reproduced, translated, or converted to any electronic medium or machine
readable form, for commercial purposes, without prior written consent from the copyright holder.
Note: Although we provide assistance on Alicat Scientic products both personally and through our literature,
it is the complete responsibility of the user to determine the suitability of any product to their application.
Conformity / Supplemental Information:
The product complies with the requirements of the Low Voltage Directive 2006/95/EC and the EMC Directive
2004/108/EC and carries the CE Marking accordingly. Contact the manufacturer for more information.
TABLE OF CONTENTS Page
GETTING STARTED 3
MOUNTING 4
PLUMBING 4
POWER AND SIGNAL CONNECTIONS 4
INPUT SIGNALS 5
Analog Input Signal 5
RS-232 / RS-485 Digital Input Signal 5
OUTPUT SIGNALS 6
RS-232 / RS-485 Digital Output Signal 6
Standard Voltage (0-5 Vdc) Output Signal 6
EPC-SERIES SINGLE VALVE PRESSURE CONTROLLER OPERATION 6
EPCD-SERIES DUAL VALVE CONTROLLER OPERATION 6
RS-232 OR RS-485 OUTPUT AND INPUT 7
Flow Vision Soware 7
Addional Compable Programs 7
Sending a Command 7
Polling Mode 7
Streaming Mode 8
Data Format 8
Sending a Setpoint via RS-232 / RS-485 8
Sending a Setpoint to a Controller with Negave and Posive
Range via RS-232 / RS-485 9
PID Tuning 9
MAINTENANCE AND RECALIBRATION 10
Technical Data for EPC and EPCD Pressure Controllers 11

3
D
C
B
A
A
B
C
D
1
2
3
4
5
6
7
8
8
7
6
5
4
3
2
1
SIZE
PART NO./DESCRIPTION
A
REV.
MATERIAL
FINISH
303L Stainless
--
DIMENSIONS ARE IN INCHES
TOLERANCES:
ANGULAR:
0 30'
TWO PLACE DECIMAL
.015
THREE PLACE DECIMAL
.005
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
ALICAT SCIENTIFIC, INC. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
ALICAT SCIENTIFIC, INC. IS
PROHIBITED.
PROPRIETARY AND CONFIDENTIAL
Dual Valve EPC .125
DATE
7/13/15
0
7641 N Business Park Dr. Tucson, AZ 85743
520-290-6060 Ph. 520-290-0109 Fax
Checked by
--
Blank #
Notes:
1. Break all sharp edges .005/.015 x 45 Deg.
Radius optional.
2. Transport as to prevent damage
3. No nicks or dings allowed on machined
surfaces.
4. Remove all burrs
5. Do not Scale Drawing
6. Use listed material when blank is unavailable
D
C
B
A
A
B
C
D
1
2
3
4
5
6
7
8
8
7
6
5
4
3
2
1
SIZE
PART NO./DESCRIPTION
A
REV.
MATERIAL
FINISH
303L Stainless
--
DIMENSIONS ARE IN INCHES
TOLERANCES:
ANGULAR:
0 30'
TWO PLACE DECIMAL
.015
THREE PLACE DECIMAL
.005
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
ALICAT SCIENTIFIC, INC. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
ALICAT SCIENTIFIC, INC. IS
PROHIBITED.
PROPRIETARY AND CONFIDENTIAL
Dual Valve EPC .125
DATE
7/13/15
0
7641 N Business Park Dr. Tucson, AZ 85743
520-290-6060 Ph. 520-290-0109 Fax
Checked by
--
Blank #
Notes:
1. Break all sharp edges .005/.015 x 45 Deg.
Radius optional.
2. Transport as to prevent damage
3. No nicks or dings allowed on machined
surfaces.
4. Remove all burrs
5. Do not Scale Drawing
6. Use listed material when blank is unavailable

















  








520-290-6060 Ph. 520-290-0109 Fax








7641 N Business Park Dr. Tucson, AZ 85743





















Rev. No. Description Date
GETTING STARTED
Inlet Connecon Port
Outlet Connecon Port
EPC-Series Pressure Controller*
Inlet Connecon Port
Outlet Connecon Port
Vent Port
EPCD-Series Pressure Controller*
* Port posions may vary according to build.

4
MOUNTING
EPC and EPCD-Series Controllers have mounng holes for convenient mounng to
at panels. These controllers are posion insensive and can be mounted in any
orientaon. The sizes and dimensions for the mounng holes are shown on page 11.




PLUMBING



Controllers with M5 (10-32) ports have O-ring face seals and require no sealant
or tape. Do not use tape with welded or O-ring ngs.
For non M5 (10-32) ports use thread sealing Teon® tape to prevent leakage
around the port threads.
 the rst two threads. This will minimize the possibility of geng
tape into the ow stream and ow body.



When changing ngs, carefully clean any tape or debris from the port connecons.
POWER AND SIGNAL CONNECTIONS
Power can be supplied to your controller through the 6 pin Micro-Fit connector.
CAUTION! 
Pin Funcon Cable Color
1DC Power input Red
2Analog Out Brown
3 Ground Black
4Serial RS-232TX / RS-485(+) Blue
5Serial RS-232RX / RS-485(-) White
6Analog Setpoint Input Green
CAUTION! 

Standard 6 Pin Micro-Fit Pin-Out
3
456
12

5
INPUT SIGNALS
Analog Input Signal
Standard 0-5 Vdc : Apply analog input to Pin 6 as shown on page 4.
0-5 Vdc is the standard analog input signal. Apply the 0-5 Vdc input signal to pin
6, with common ground on pin 3.
Oponal 0-10 Vdc: If specied at me of order, a 0-10 Vdc input signal can be
applied to pin 6, with common ground on pin 3.
Oponal 4-20 mA: If specied at me of order, a 4-20 mA input signal can be
applied to pin 6, with common ground on pin 3.
NOTE: This is a current sinking device. The receiving circuit is essenally a
250ohm resistor to ground.
CAUTION! 



Wiring your EPC Cable into a DB9 RS-232 or RS-485 adaptor
To use the RS-232 or RS-485 input signal, connect the RS-232 / RS-485 Output
Signal (Pin 5), the RS-232 / RS-485 Input Signal (Pin 3), and Ground (Pin 8) to
your computer serial port as shown below. (See page 7 for details on accessing
RS-232 / RS-485 input.)



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9876
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9876
15 3 24 1 532 4
Serial Cable End PC Serial Port
9 Pin Serial Connecon 6 Pin Micro-Fit Connecon
Pin Funcon Funcon Pin
6 Ground Ground 1
5 Transmit Receive 2
4Receive Transmit 3
DB9 to Micro-Fit Connecon for RS-232 / RS-485 Signals
Please Note: DB9 adaptor drawings shown represent the face of the cable,
wiring ports at the back of the adaptor will be mirrored.

6
OUTPUT SIGNALS
RS-232 / RS-485 Digital Output Signal
To use the RS-232 or RS-485 output signal, it is necessary to connect the RS-
232/ RS-485 Output Signal, the Input Signal, and Ground to your computer
serial port as shown on page 5. (See page 7 for details on accessing RS-232 /
RS-485 output.)
Standard Voltage (0-5 Vdc) Output Signal
Controllers equipped with a 0-5 Vdc will have this output signal available. This
voltage is usually in the range of 0.010 Vdc for zero ow and 5.0 Vdc for full-scale
ow. The output voltage is linear over the enre range. Ground for this signal is
common on Pin 3. Other output opons include 0-10 Vdc, 1-5 Vdc and 4-20 mA.
EPC-SERIES SINGLE VALVE PRESSURE CONTROLLER OPERATION
Alicat Scienc EPC-Series Pressure Controllers incorporate a digital pressure
gauge with a single control valve and circuitry. The integrated PID loop measures
the pressure, compares it with the setpoint, and adjusts the valve accordingly at
1000 mes per second.
The response me of the system will depend on the operang condions and the
PID tuning of the device.
Plumbing
EPC-Series Pressure Controllers are normally intended to control the process
pressure downstream of the controller. In order for this to occur, a supply pressure
greater than the full scale pressure control range of the device, not to exceed 150
psig, should be connected to the “IN” port.
EPCD-SERIES DUAL VALVE PRESSURE CONTROLLER OPERATION
Alicat Scienc EPCD-Series Closed Volume Pressure Controllers incorporate a
digital pressure gauge with dual control valves and circuitry. The integrated PID
loop measures the pressure, compares it with the setpoint, and adjusts either the
Inlet or Exhaust valve accordingly at 1000 mes per second.
The response me of the system will depend on the size of the volume being
controlled, the operang condions, and the PID tuning of the device. The
controllers are intended for use with clean, non-corrosive gases only.
They are designed with a feed port, a process port, and an exhaust port. This
allows the controllers to raise and lower the pressure of a closed system within
the operang range of the controller without wasng gas under constant
pressure condions.
Plumbing
EPCD-Series Dual Valve Pressure Controllers are commonly ordered with
custom port locaons.
Connect your EPCD into your process via the “OUT” port of the unit. This is the
“Process” port.
Connect a supply pressure greater than the full scale pressure control range of
the device, not to exceed 150 psig, to the “IN” port.
The “VENT” port can vent to atmosphere if the applicaon is suitable, or to a
collecon network if necessary.
The pressure at the vent port should be at atmospheric pressure or below to
allow the controller to be used over its full scale range.

7
RS-232 / RS-485 OUTPUT AND INPUT
EPC and EPCD pressure instruments come standard with integrated mul-drop
RS-232 or RS-485 as ordered.
Flow Vision Soware
Flow Vision is an aordable soware program that interfaces with RS-232 or
RS-485 and is compable with most of the aforemenoned ow and pressure
instruments.
The graphical user interface (GUI) provides automac conguraon, session saving
for easy conguraon and experiment setup reloads, data capturing and logging
(including a graphing tool), simple script building for automang meter and control
command sequences, soware alarms and support for mulple devices.
Flow Vision SC™ is for general use with up to 26 dierent devices, while Flow
Vision MX™ is specically designed for gas mixing applicaons.
Addional Compable Programs:
Many serial communicaon type soware packages including PuTTy and LabVIEW
are also compable with these instruments. To set up serial communicaon it is
important to note which COM port the device is connected to and the baud rate on
the device (default 19200).
It may also be useful to make sure the program will move to the next line when
pressing “Enter” or “Return”. The number of data bits should be set to 8, and the
number of stop bits should be set to 1. Parity and ow control should be disabled.
Not all programs have these opons and care should be taken to determine the
proper communicaon setup with the desired program.
Sending a Command
In this secon, a command will be denoted with a dierent font. For example,
command<CR> . <CR> will be used to symbolize a carriage return. How a
carriage return is entered is dependent on the serial communicaon program
being used.
With Serial Terminal, this can commonly be accomplished by pressing “Enter”
or “Return”. Parenthesis denote a value that must be lled in by the user.
For example,(unit ID)<CR> should be changed to A<CR> when using a
device with Unit ID “A”. It may also be useful to note that commands are case
insensive. For example, A<CR> is equivalent to a<CR>.
Polling Mode
All Alicat devices are sent in Polling Mode with Unit ID A unless otherwise
requested. Polling a device will return a data frame of the current
measurements in the device in units shown on the display. See Data Format,
later in this secon, for more informaon. Each unit may be polled individually
using the command (unit ID)<CR>.
A device’s Unit ID may be changed using the command (current unit
ID)@=(desired unit ID)<CR>. The Unit ID can also be changed via the
front panel using the RS-232 / RS-485 communicaon select menu.
Care should be taken not to assign the same unit ID to more than one device on
a single COM port. Up to 26 units may be connected simultaneously as Unit IDs
between A and Z are allowed.

8
Streaming Mode (RS-485 units do not have streaming mode)
In Streaming Mode, a device will automacally output the data stream at a pre-
determined rate. The default rate is set to 50 ms. Only one unit on a given COM
port may be in streaming mode at a me.
To change a unit from Polling Mode to Streaming Mode, type (unit
ID)@=@<CR>. This is equivalent to changing the unit ID to “@”. If data does
not appear, check all the connecons and COM port sengs.
When sending a command to a unit in streaming mode, the ow of informaon
will not stop while the user is typing; and the typed text may not be readable
depending on the terminal sengs. If the unit does not receive a valid
command, it will ignore it. If in doubt, simply perform another carriage return
and start again.
To change a unit from Streaming Mode to Polling Mode, type @@=(unit
ID)<CR>. If entered correctly, the data stream will stop and the device will
now be in polling mode.
Data Format
The data frame on the screen represents the current measurements in the
device in the units shown on the display. By default, pressure controllers are
congured to output three columns of data
All data is displayed in the “device units” selected on the unit. Devices come
standard with units of PSIA or PSIG, depending on the type of the device.
The rst column is the unit ID. This column will be excluded if the device is in
streaming mode. The next column is pressure, and the third column will display
setpoint.
For example, suppose a controller with unit ID A was ordered with units of inHgG
and currently has a setpoint value set to 50.42 inHgG. The data frame may read:
A +50.42 50.42
Unit ID Pressure Setpoint
EPC/EPCD-Series Pressure Controller Data Format
Addional columns, including status codes, may be present to the right of the
last column.
Sending a Setpoint via RS-232 / RS-485
EPC’s can be ordered in analog input mode or in RS-232/RS-485 input mode. If
you’ve ordered the EPC in RS-232/R-S485 input mode the following secon will
provide instrucons on sending a setpoint via RS-232/RS-485.
If you’ve ordered the EPC in analog input mode and wish to change over to
RS-232/RS-485 input mode, you must read and adjust register 20 in the 16
bit programming of your EPC. Please contact the factory for instrucons
on changing from Analog to RS-232/RS-485 input mode via RS-232/RS-485
adjustment.
To send a setpoint via RS-232 / RS-485:
Method 1: Setpoint may be set as a oang point number in serial
communicaon using the setpoint command (unit ID)S(oating
point number)<CR>. For example, AS4.54<CR> changes the setpoint for
unit “A” to 4.54 in the current device units.
Method 2: The setpoint can also be set in reference to a poron of the full
scale. Type (unit ID)(integer)<CR>. Values between 0 and 64000 are
acceptable, which correspond linearly to 0 and 100% full scale ow respecvely.
Once a setpoint is accepted, the data frame will be returned with the setpoint
column changed accordingly.

9
The formula for performing linear interpolaon is as follows:
Value = (desired setpoint) X 64000 / (full Scale)
For example, when changing the setpoint on a 100 PSIA full scale controller to
35 PSIA, the following value should be entered:
22400 = (35 PSIA) X 64000 / (100 PSIA)
Sending a Setpoint to a Controller with Negave and Posive Range
via RS-232 / RS-485
For a controller with a negave and posive range, the setpoint command may
be sent in either of the above two methods with the following changes:
Using Method 1, a negave setpoint may be set using a negave sign in the
command. For example, AS-4.54<CR> changes the setpoint for units “A” to
-4.54 in the current device units.
Using Method 2, values between 0 and 64000 are acceptable which correspond
linearly to the minimum and maximum pressure, respecvely. The formula to
perform linear interpolaon for a negave and posive ranged controller is as follows:
Value = (desired setpoint + minimum pressure) X 64000 / (maximum pressure -
minimum pressure)
For example, when changing the setpoint on a -10 PSIG to 10 PSIG ranged
controller to -3 PSIG, the following value should be entered.
20800 = (-3 PSIG + -10 PSIG) X 64000 / 10 PSIG- (-10 PSIG)
PID Tuning your EPC and EPCD over RS-232/RS-485:
The EPC and EPCD series of pressure controllers have an integrated PID loop
that measures the pressure, compares it with the setpoint, and adjusts the valve
accordingly at 1000 mes per second. This PID tuning governs the control speed,
control stability, overshoot, and general performance of the EPC or EPCD. If
you encounter issues with valve stability, oscillaon or speed, ne tuning these
parameters may resolve the problem. Alicat controllers allow you to adjust the
Proporonal, Integral and Dierenal terms of the PID control loop.
Knowing how to change PID tuning, and knowing how to do it correctly and aain
the results you desire are two very dierent things. The following secon covers
the theory/operaonal characteriscs of the PID parameters:
The PD algorithm is the PID algorithm used on most Alicat controllers. It is divided
into two segments:
The rst compares the process value to the setpoint to generate a proporonal
error. The proporonal error is mulplied by the ‘P’ gain, with the result added to
the output valve drive.
The second operates on the present process value minus the process value during
the immediately previous evaluaon cycle.
This ‘velocity’ term in mulplied by the ‘D’ gain, with the result subtracted
from the output valve drive. The above addions to and subtracons from the
output drive register are carried over from process cycle to process cycle, thus
performing the integraon funcon automacally.
Increasing the ‘P’ gain will promote the tendency of the system to overshoot,
ring, or oscillate. Increasing the ‘D’ gain will reduce the tendency of the system to
overshoot.

10
The PD2I algorithm is a PID algorithm used primarily for high performance
pressure and ow control applicaons. It exhibits two basic dierences from the
PD algorithm that most controllers ulize.
1. Instead of applying a damping funcon based upon the rate of change of the
process value, it applies a damping funcon based upon the square of the rate of
change of the process value.
2. The damping funcon is applied directly to the proporonal error term before
that term is used in the proporonal and integral funcons of the algorithm.
This provides a certain amount of ‘look ahead’ capability in the control loop.
Because of these dierences, you will note the following:
1. Increasing ‘P’ gain can be used to damp out overshoot and slow oscillaons in
pressure controllers. You will know that ‘P’ gain is too high, when the controller
breaks into fast oscillaons on step changes in setpoint. On ow controllers,
too low a ‘P’ gain results in slower response mes. Too high a ‘P’ gain results in
overshoot and/or slow oscillaon. A good starng value for ‘P’ gain is 200.
2. If the unit was originally shipped with the PD2I algorithm selected, the ‘D’ gain
value should be le at or near the factory seng because it relates primarily to
the system phase lags. If you are changing from the default algorithm to the PD2I
algorithm, you should start with a ‘D’ gain value of 20.
3. The ‘I’ gain is used to control the rate at which the process converges to the
setpoint, aer the inial step change. Too low a value for ‘I’ gain shows up as a
process value that jumps to near the setpoint and then takes awhile to converge
the rest of the way. Too high a value for ‘I’ gain results in oscillaon. A good
starng value for the ‘I’ gain is 200.
MAINTENANCE AND RECALIBRATION
General: EPC and EPCD-Series controllers require minimal maintenance. The single
most important thing that aects the life and accuracy of these devices is the
quality of the gas being measured. The instruments are designed to measure clean,
dry, non-corrosive gases.
Recalibraon: The EPC device is an OEM product calibrated to NIST traceable
standards at the me of manufacture. As an OEM device there is not a factory
recommended periodic recalibraon cycle. Recalibraon can be requested at the
user’s discreon/requirement. Before calling to schedule a recalibraon, please
note the serial number on the back of the device.
Cleaning: EPC and EPCD-Series controllers require no periodic cleaning. If
necessary, the outside of the controller can be cleaned with a so dry cloth.
Avoid excess moisture or solvents.
For repair, recalibraon or recycling of this product, contact:
Alicat Scienc, Inc.
7641 N Business Park Drive
Tucson, Arizona 85743
USA
Ph. 520-290-6060
Fax [phone]
email: [email protected]
Web site: www.alicat.com