API Weinschel 420 Series User manual

MANUAL IM672
Operation & Installation Manual Revision C
Operation and Installation Manual
Model 420X Series
Digital Attenuators
This documentation may not be reproduced in any form, for
any purpose unless authorized in writing by Weinschel, a
part of API Technologies Corp.

MANUAL IM672
Table of Contents Page 2
Table of Contents
Table of Contents............................................................................................................................................2
1. Safety Summary .........................................................................................................................................4
1.1. Definitions ............................................................................................................................................4
1.2. Detailed Precautions..............................................................................................................................4
1.3. Electrostatic Discharge Sensitive (ESDS) .................................................................................................4
2. General Information ....................................................................................................................................5
2.1. Purpose ................................................................................................................................................5
2.2. Equipment Overview .............................................................................................................................5
3. Specifications..............................................................................................................................................5
3.1. Electrical Specifications..........................................................................................................................5
3.2. Timing Specifications .............................................................................................................................5
3.3. 420X Series modules .............................................................................................................................6
3.4. DC Power Input ....................................................................................................................................8
4. Installation and Operation ...........................................................................................................................8
4.1. Mounting ..............................................................................................................................................8
4.2. RF Connectors & Cable Installation.........................................................................................................8
4.3. Control Connectors................................................................................................................................8
4.3.1 AUX mode digital IO (10-pin 0.1” Header)..........................................................................................8
4.3.2 USB Mini-B.......................................................................................................................................9
4.4. USB/AUX Mode Interface Selection.........................................................................................................9
4.5. AUX Interface Modes...........................................................................................................................10
4.5.1 AUX Modes ....................................................................................................................................10
4.5.2 PIO Mode.......................................................................................................................................10
4.5.3 SPI Mode .......................................................................................................................................10
4.5.4 I2C Mode .......................................................................................................................................10
4.5.5 SPI and I2C Attenuation Data Format ..............................................................................................11
4.5.6 UART Mode....................................................................................................................................14
4.6. AUX Application Modes ........................................................................................................................14
4.6.1 PIOSW Mode..................................................................................................................................14
4.6.2 PULSE Mode...................................................................................................................................14
4.6.3 FADE Mode ....................................................................................................................................15
4.6.4 USB Mode AUX pin usage................................................................................................................16
4.6.5 USB ...............................................................................................................................................16
5. Command Operation .................................................................................................................................17
5.1. Command Reference ...........................................................................................................................18
5.2. Application Specific Commands ............................................................................................................18
ATTN ..................................................................................................................................................18
ATTN?.................................................................................................................................................19
STEPSIZE ............................................................................................................................................19
STEPSIZE? ..........................................................................................................................................19
INCR...................................................................................................................................................19
DECR ..................................................................................................................................................19
FADE...................................................................................................................................................20
FADE? .................................................................................................................................................20

MANUAL IM672
Table of Contents Page 3
5.3. 488.2 Common Commands ..................................................................................................................20
*CLS ...................................................................................................................................................20
*IDN? .................................................................................................................................................20
*OPC?.................................................................................................................................................21
*ESR? .................................................................................................................................................21
*RST...................................................................................................................................................21
*TST? .................................................................................................................................................21
ERR?...................................................................................................................................................21
5.4. Setup and Configuration Commands.....................................................................................................22
SET AUX..............................................................................................................................................22
SET USB..............................................................................................................................................22
SET ALIAS ...........................................................................................................................................22
SET BAUDRATE ...................................................................................................................................23
SET ATTN............................................................................................................................................23
SET I2CADDR ......................................................................................................................................23
SET I2CTRIG .......................................................................................................................................23
SET WPU.............................................................................................................................................23
SET PULSE ..........................................................................................................................................24
SET FADE............................................................................................................................................24
RUN AUX.............................................................................................................................................24
SHOW SET ..........................................................................................................................................25
SHOW VERSION ..................................................................................................................................25
FACTORY PRESET ................................................................................................................................25
5.5. Misc. Commands .................................................................................................................................26
ALIAS? ................................................................................................................................................26
ATTNIO...............................................................................................................................................26
ATTNIO? .............................................................................................................................................26
CONSOLE ............................................................................................................................................26
CONSOLE? ..........................................................................................................................................27
DELAY.................................................................................................................................................27
REBOOT..............................................................................................................................................27
REPEAT...............................................................................................................................................27
RFCONFIG? .........................................................................................................................................28
RUN LOADER.......................................................................................................................................28
SYSTEST .............................................................................................................................................28
6. USB Driver Installation ..............................................................................................................................30
6.1. awusbcdc.inf Installation File ...............................................................................................................33
6.2. Updating the 420X Firmware using USB HID Bootloader ........................................................................35
6.2.1 Method 1 .......................................................................................................................................36
6.2.2 Method 2 .......................................................................................................................................36
7. Factory Service and Repairs .......................................................................................................................40
8. Contacting Weinschel ................................................................................................................................41
8.1. Manufacturer Warranty........................................................................................................................41
9. Revision History ........................................................................................................................................42

MANUAL IM672
Safety Summary Page 4
1. Safety Summary
1.1. Definitions
The following definitions apply to WARNINGS, CAUTIONS, and NOTICES may found throughout this manual.
WARNING: An operating or maintenance procedure, practice, statement, condition, etc., which, if not strictly
observed, could result in injury and/or death of personnel. Do not proceed beyond a WARNING symbol until all the
indicated conditions have been fully understood and/or met.
CAUTION: An operating or maintenance procedure, practice, statement, condition, etc., which, if not strictly
observed, could result in damage or destruction of the equipment or long-term health hazards to personnel. Do not
proceed beyond a CAUTION symbol until all the indicated conditions have been fully understood and/or met.
NOTICE: An essential operating or maintenance procedure, condition, or statement that must be highlighted.
1.2. Detailed Precautions
The following WARNINGS, CAUTIONS and NOTES appear throughout the text of this manual and are repeated
here for emphasis.
All procedures and/or steps identified as must be followed exactly as written and according to
industry accepted ESDS device handling procedures. Failure to comply may result in ESD
damage.
1.3. Electrostatic Discharge Sensitive (ESDS)
The equipment documented in this manual contains certain Electrostatic Discharge Sensitive (ESDS) components
or parts. Therefore, certain procedures/steps are identified by the use of the symbol . This symbol is used in
two ways:
When the ESDS symbol is placed between a paragraph and title, that paragraph, including all
subparagraphs, is considered ESDS device handling procedure.
When the ESDS symbol is placed between a procedure/step number and the text, all of that procedure is
considered an ESDS device handling procedure.
All procedures and/or steps identified as ESDS must be followed exactly as written and according to accepted ESDS
device handling procedures. Failure to comply may result in ESDS damage

MANUAL IM672
General Information Page 5
2. General Information
2.1. Purpose
This manual contains setup and operation information for the Weinschel Model 420X series, Solid State
Programmable Attenuators. This manual is to be used in conjunction with the operation and installation of the
Model 420X Series. The manual also provides a description of the assembly and general maintenance procedures.
2.2. Equipment Overview
The 420X series Solid State Programmable Attenuators provide for control via either USB or a variety of digital
interfaces through the AUX mode connector, including parallel input (PIO), I2C, SPI, or a logic-level UART interface.
AUX mode selection is done via a USB command and can be changed by the user.
3. Specifications
The electrical and timing specifications of model 420X are listed below. Refer to appropriate ICD drawings for more
specifications about each module.
3.1. Electrical Specifications
Parameter
Min
Typical
Max
Comments
DC Power (AUX pin 9)
VDC Supply Voltage
3.3V
5V
16V
Supply voltage 3.5V MIN for full spec
compliance
IDC Supply Current (VDC=5V)
15mA
25mA
AUX IO
Note: All AUX IO have weak pullups enabled by default
VIH Input High Voltage
VDC= 3.3V to 4.5V
VDC= 4.5V to 16V
2.0V
VDC+0.3
2.0V
5.0V
VIL Input Low Voltage
VDC= 3.3V to 4.5V
VDC= 4.5V to 16V
-0.3V
0.15VDC
-0.3V
0.8V
VOH Output High Voltage
2.6V
ILOAD = 3mA
VOL Output Low Voltage
0.6V
ILOAD = 3mA
IPU Pullup Current
25uA
130uA
300uA
User selectable
USB
USB Supply Voltage (VBUS)
4.4V
5.25V
D+/D- Input Voltage
3.6V
3.2. Timing Specifications
Parameter
Min
Typ
Max
Comments
General
RF switching speed
Model 4205A
400ns
Model 4209
35ns
10% RF to 90% RF
Model 4204
1µs
10% RF to 90% RF
Power up time
50ms
DC power to first command
Attenuation update rate
Model 4205A
200KHz
Model 4209
100KHz
Command processing time
2ms
USB mode
PIO mode

MANUAL IM672
Specifications Page 6
Parameter
Min
Typ
Max
Comments
PIO input change to RF
change
Model 4205A
3µs
5µs
Model 4209
3µs
10µs
Model 4204
8µs
50% CTRL to 90% RF
PIOSW input change to RF
Model 4205A
1µs
Single line input
Model 4209
5µs
Single line input
SPI mode
SCLK clock frequency
10MHz
SSN setup/hold time
100ns
SSN falling/rising edge to SCLK
SDI data setup time
25ns
SDI to SCLK rising edge
I2C mode
SCL clock frequency
400KHz
RESETN width
10µs
RESETN low pulse width (optional)
TRIG
1µs
TRIG input, rising/falling edge
(optional)
UART mode
Baud rate
9600
115K
3.3. 420X Series modules
Figure-1 shows the 4205A series module.
Figure-1: 4205A Series attenuator

MANUAL IM672
Specifications Page 7
Figure-2 shows the 4209 series module.
Figure-2:4209 Series Attenuator
Figure-3 shows the 4204 series module.
Figure-3: 4204 Series Attenuator

MANUAL IM672
Installation and Operation Page 8
3.4. DC Power Input
The 420X series attenuators can be powered from either the USB VBUS (5V) or the AUX VDC input. While USB
operates at a nominal 4.75V-5.25V range, the AUX VDC supply input can accept a wider range of voltage, from
3.3V-16VDC. If both AUX power and USB VBUS are present then the device will be powered from whichever provides
the higher voltage. For AUX VDC voltages < 5V the input logic signals are limited to the VDC supply voltage.
Otherwise, input logic signals are limited to a max voltage of 5V.
4. Installation and Operation
4.1. Mounting
The 420X Attenuator is supplied with 12 mounting holes. Refer to the appropriate Weinschel Specification/ICD
drawing for the mounting hole dimensions and locations.
When applying a signal to the RF connectors, DO NOT exceed the maximum allowable power
level specifications of the unit.
Do not over torque the SMA connectors more than 10 inch pounds. Damage may occur.
4.2. RF Connectors & Cable Installation
The Model 4205A series contains two SMA female connectors labeled J1 and J2 that mate nondestructively with
SMA male connectors per MIL-STD-39012. The Model 4209 series modules are available with 2.92 mm, 2.4 mm,
or SMA female connectors and the 4204 series module generally comes with type F 75Ω female connectors. Refer
to appropriate ICD to determine the type of connectors for a given part number. Weinschel recommends a torque
value of 7 to 8 inch pounds when connecting any cable to the attenuator's RF connectors.
4.3. Control Connectors
4.3.1 AUX mode digital IO (10-pin 0.1” Header)
A variety of control interfaces can be used with the AUX Connector. Options include Parallel IO, I2C, SPI, UART,
and USB. The SET AUX command allows the user to select the control interface for the AUX Connector. The table
below describes the pinouts for the various control modes.
4205A and 4 204 Series
PIN
SIGNAL
PIO
I2C
SPI
UART
USB
4205A-31.5
4205A-63.5
4205A-95.5*
& 4204-95.5
4205A-
127*
1
D0
0.25dB
0.25dB
0.5dB
0.5dB
A0
2
D1
0.5dB
0.5dB
1dB
1dB
A1

MANUAL IM672
Installation and Operation Page 9
4205A and 4 204 Series
PIN
SIGNAL
PIO
I2C
SPI
UART
USB
4205A-31.5
4205A-63.5
4205A-95.5*
& 4204-95.5
4205A-
127*
3
D2
1dB
1dB
2dB
2dB
A2
RXD
4
D3
2dB
2dB
4dB
4dB
A3
TXD
5
D4
4dB
4dB
8dB
8dB
TRIG
SSN
6
D5
8dB
8dB
16dB
16dB
RESETN
SCLK
7
D6
16dB
16dB
32dB
32dB
SCL
SDI
8
D7
--
32dB
32dB
64dB
SDA
BOOTN
9
VDC
VDC
VDC
VDC
VDC
VDC
VDC
VDC
10
GND
GND
GND
GND
GND
GND
GND
GND
GND
*0.25dB accessible in serial or USB modes
4209 Series
PIN
SIGNAL
PIO
I2C
SPI
UART
USB
4209-31.5
4209-63
4209-94.5
1
D0
0.5dB
0.5dB
0.5dB
A0
2
D1
1dB
1dB
1dB
A1
3
D2
2dB
2dB
2dB
A2
RXD
4
D3
4dB
4dB
4dB
A3
TXD
5
D4
8dB
8dB
8dB
TRIG
SSN
6
D5
16dB
16dB
16dB
RESETN
SCLK
7
D6
--
32dB
32dB
SCL
SDI
8
D7
--
--
32dB
SDA
BOOTN
9
VDC
VDC
VDC
VDC
VDC
VDC
VDC
10
GND
GND
GND
GND
GND
GND
GND
GND
4.3.2 USB Mini-B
The table below describes the pinouts of the USB connector.
PIN
SIGNAL
DESCRIPTION
1
VBUS
+5V
2
D-
Data-
3
D+
Data+
4
ID
unused
5
GND
Ground
4.4. USB/AUX Mode Interface Selection
The main operating mode of the 420X is determined from the DC Power input. At power on the USB connector
VBUS pin is examined, and if detected then the unit will operate in USB mode. Otherwise the UUT will operate in
one of the digital AUX modes powered via the AUX VDC power input. It is allowable to have both cables connected
at the same time.
If an AUX mode is currently active the unit will detect a USB connect event and switch over to USB mode
automatically.
Typically you would return to AUX mode by disconnecting the USB cable (or removing USB power). The USB
command RUN AUX also allows switching from USB mode to an AUX mode via command, and does not require the

MANUAL IM672
Installation and Operation Page 10
AUX connector VDC power to be present. This is usefully in certain AUX application modes (see PULSE and FADE
modes).
4.5. AUX Interface Modes
4.5.1 AUX Modes
There are four user-selectable digital interface AUX modes: PIO, I2C, SPI, and UART. In addition there are three
AUX application modes (PIOSW, PULSE, and FADE) that allow the generation of RF patterns when operating stand-
alone. The AUX mode selection is done via USB command (see SET AUX) and is stored in non-volatile memory
(NVM) so that changes to the mode will be automatically applied at startup. The AUX digital interface pins vary in
function depending on the selected mode. Each pin can have a software programmable weak pullup assigned,
which is enabled by default for all pins (see SET WPU). The weak pullup will provide a logic high to the pin if left
unconnected.
4.5.2 PIO Mode
In PIO mode there are up to eight parallel digital input signals, D0-D7. Each input represents a dB value setting,
with a logic low input = 0dB setting and a logic high = dB value for each control input as shown in the PIO column
of the J1 AUX mode table.
4.5.3 SPI Mode
SPI mode is a serial interface that operates as a 16-bit serial-in shift register and latch comprised of three signals:
SSN low-active chip select, SCLK serial shift clock, and SDI serial data in. Data present on the SDI input is clocked
into the shift register on the rising edge of SCLK. Data is comprised of a single 8-bit value for the 31.5dB, 63.5dB
models along with model 4209-95.5 dB. Data is comprised of 16-bits, organized into two bytes, for the 4205A-
95.5dB and 4205A-127dB models which provides access to the 9th 0.25dB bit. Serial data is clocked in MSB first to
LSB and must be in multiples of 8-bits. SSN must be asserted low before sending data to the attenuator, allowing
multiple attenuators to be controlled via the same SCLK and SDI signals. Attenuation changes are updated on the
rising edge of SSN after all data bits have been clocked in.
Note that all models will accept 16-bits of programming data. The data should be left-justified in the 16-bit word
so that the MSB is the first bit sent and any unused bits should be set to 0. The first byte represents the D7-D0
values shown in the PIO mode table. The first bit of the second byte ('D-1') represents the 0.25dB value for the
4205A-95.5 and 4205A-127. Refer to the Attenuation Data Format section for examples on formatting 16-bit data.
D7 D6 D5 D4 D3 D2 D1 D0
SSN
SCLK
SDI D-1 D-2 0 0 0 0 0 0
MSB LSB OPTIONAL 2ND BYTE
(0.25dB FOR 4205A-95.5)
4.5.4 I2C Mode
I2C mode is a serial interface that uses two lines: SCL serial clock and SDA serial data, along with the optional
controls RESETN, TRIG, and address bits A3-A0. Both the SCL and SDA connections are bidirectional open-drain
lines, each requiring pull-up resistors to the logic supply voltage (5V max).

MANUAL IM672
Installation and Operation Page 11
I2C messages consist of a device address byte, register select byte, and one or more data bytes depending on the
register. The Register address will automatically increment after each byte transferred. Messages are framed using
the standard I2C START, STOP, and ACK conditions. The I2C master should support clock stretching as the 4205A
will hold the SCL clock low during the byte ACK phase until the data is accepted by the 4205A.
START
DEV ADDR
REG ADDR
DATA
<DATA>
STOP
The 4205A is a slave I2C device that supports 7-bit slave addressing. The slave address can be set via hardware
address pins A3-A0 on the AUX connector or via USB command (see SET I2CADDR). Using the hardware address
pins allows for up to 16 attenuators to share the same bus. In this mode the three upper bits of the address byte
are fixed at 0b010. The I2C R/W bit is the LSB of the address byte, providing for device addresses 0b0100000x –
0b0101111x (0x40-0x5E).
I2C Device Address
7
6
5
4
3
2
1
0
0
1
0
A3
A2
A1
A0
R/W
010 : fixed bits
A3-A0 : addr bits
R/W bit : WR=0, RD=1
A device address can also be assigned using the USB SET I2CADDR command which allows the use of all 7 D7-D1
address bits, with the exception of the reserved address 0. A software assigned address overrides the hardware
A3-A0 pins and connections to these pins are ignored. When specifying a software address always use the full 8-
bit byte value, with bit 0 set to 0 (it will be ignored as this is the I2C R/W bit). Setting the I2CADDR to 0 will remove
any software assigned address and revert back to hardware addressing mode.
I2C mode provides two optional control inputs: RESETN and TRIG. RESETN is a low-active signal that will reset and
reinitialize the attenuator. The TRIG signal allows attenuation changes to be performed on the TRIG input becoming
asserted instead of changing immediately when the I2C command is sent, and can be programmed to be active-
high or active-low (see I2CTRIG command). This can be used to synchronize multiple attenuators.
Register 1 –Echo Test Register
This is a general scratchpad register. Any 8-bit value written to this register can be read back and used to check
communications.
Register 2 –ATTN_LB Low Byte Register
The ATTN_LB register is the lower byte of attenuation data used for attenuators with more than 8-bits of
programming data (4205A-95.5 and 4205A-127). This register should be written to prior to writing the ATTN_HB
register.
Register 3 –ATTN_HB High Byte Register
The ATTN_HB register is used to set the upper byte of attenuation data for units with > 8-bits, or the single 8-bit
programming data for units that require only a single byte. The attenuator setting will be changed when this register
is written unless external triggering has been enabled.
4.5.5 SPI and I2C Attenuation Data Format
The data programming format is the same for both I2C and SPI modes; either a single 8-bit value or a 16-bit word
value. Either method may be used as long as the data properly formatted. 16-bit word data must be left-justified

MANUAL IM672
Installation and Operation Page 12
and sent as two 8-bit bytes. In SPI mode 16-bit data should be written high-byte then low-byte, and the value will
be loaded on the rising edge of the SSN signal. In I2C mode the ATTN_LB low-byte register should be written prior
to setting the ATTN_HB register since in this mode accessing the high-byte register loads the value into the
attenuator.
The 4205A-31.5, 4205A-63.5 and all 4209 models use a single byte to represent the D0-D7 programming bits. For
these units a single byte write to the ATTN_HB register is all that is required. The 4205A-95.5 and 4205A-127
models require 9-bits of data to access the 0.25dB bit, so two bytes must be written if control of the 0.25dB bit is
desired.
Example 1: 4205A-31.5 using hardware addr pins A3-A0 set to 0100
Desired attenuation: 10.25dB
Compute the device address by combining the fixed upper portion, the addr pin setting, and the R/W bit=0 (write):
DEV ADDR = (0b010 << 5) + (0b0100 << 1) + 0 = 0b01001000 = 72 = 0x48
Compute the programming value. Each bit represents 0.25dB, so setting = INT((dB * 100)/25), or simply multiply
the dB value by 4 and use the integer result:
VAL = 10.25dB * 4 = 41 = 0x29 = 0b00101001
There is only a single byte required, so this value should be programmed into register 3 (ATTN_HB)
DEV ADDR=4 + R/W=0
REG ADDR = 3
ATTN_HB=41
S
0
1
0
0
1
0
0
0
A
0
0
0
0
0
0
1
1
A
0
0
1
0
1
0
0
1
A
P
Where S=START, P=STOP, and A=ACK
Example 2: 4205A-127 using hardware addr pins A3-A0 set to 0011
Desired attenuation: 101.25dB
Compute the device address by combining the fixed upper portion, the addr pins, and the R/W bit=0 (write):
ADDR = (0b010 << 5) + (0b0011 << 1) + 0 = 0b01000110 = 70 = 0x46
Compute the programming value. Each bit represents 0.25dB, so setting = INT((dB * 100)/25), or simply multiply
the dB value by 4 and use the integer result:
VAL = 101.25dB * 4 = 405 = 0x0195
Since we require 9-bits of data, left-justify the 16-bit programming word by shifting it left 7 times:
VAL = 0x0195 << 7 = 0xCA80
Splitting the word into two bytes gives a setting of ATTN_HB = 0xCA and ATTN_LB = 0x80 which need to be
programmed into registers 2 (LB) and 3 (HB):
DEV ADDR=3 + R/W=0
REG ADDR = 2
S
0
1
0
0
0
1
1
0
A
0
0
0
0
0
0
1
0
A
ATTN_LB=0x80
ATTN_HB=0xCA
1
0
0
0
0
0
0
0
A
1
1
0
0
1
0
1
0
A
P
Example 3: 4205A-95.5 using hardware addr pins A3-A0 set to 0010
Desired attenuation: 68.75dB

MANUAL IM672
Installation and Operation Page 13
Compute the device address by combining the fixed upper portion, the addr pins, and the R/W bit=0 (write):
ADDR = (0b010 << 5) + (0b0010 << 1) + 0 = 0b01000100 = 68 = 0x44
Compute the programming value. Each bit represents 0.25dB, so setting = INT((dB * 100)/25), or simply multiply
the dB value by 4 and use the integer result:
VAL = 68.75dB * 4 = 275 = 0x0113
Since we require 9-bits of data, left-justify the 16-bit programming word by shifting it left 7 times:
VAL = 0x0113 << 7 = 0x8980
Splitting the word into two bytes gives a setting of ATTN_HB = 0x89 and ATTN_LB = 0x80 which need to be
programmed into registers 2 (LB) and 3 (HB):
DEV ADDR=2 + R/W=0
REG ADDR = 2
S
0
1
0
0
0
1
0
0
A
0
0
0
0
0
0
1
0
A
ATTN_LB=0x80
ATTN_HB=0x89
1
0
0
0
0
0
0
0
A
1
0
0
0
1
0
0
1
A
P
Example 4: Read 16-bit attenuation data from 4205A-95.5 with hardware addr pins A3-A0 set to 0010
Compute the device address by combining the fixed upper portion, the addr pins, and the R/W bit=0 (write):
ADDR = (0b010 << 5) + (0b0010 << 1) + 0 = 0b01000100 = 68 = 0x44
To perform a device read you must first set the desired register address. To read the single ATTN_HB register send
the DEV ADDR with R/W=0 (write) and the REG ADDR = 3. Next, send an I2C RESTART followed by the DEV ADDR
with R/W = 1 (read). The I2C master should then read the byte and send a NACK to terminate the transaction.
DEV ADDR=2 + R/W=0
REG ADDR = 3
S
0
1
0
0
0
1
0
0
A
0
0
0
0
0
0
1
1
A
DEV ADDR=3 + R/W=1
R
0
1
0
0
0
1
1
1
A
ATTN_HB=0x89
1
0
0
0
1
0
0
1
N
P
To read multiple bytes the I2C master should read the first byte and send an ACK, then read the second byte with
a NACK to terminate the transaction.
DEV ADDR=2 + R/W=0
REG ADDR = 2
S
0
1
0
0
0
1
0
0
A
0
0
0
0
0
0
1
0
A
DEV ADDR=2 + R/W=1
R
0
1
0
0
0
1
0
1
A
ATTN_LB=0x80
ATTN_HB=0x89
1
0
0
0
0
0
0
0
A
1
0
0
0
1
0
0
1
N
P
Where S=START, R=RESTART, P=STOP, A=ACK, and N=NACK
To compute the attenuation value shift the 16-bit word right 7 times: 0x8980 >> 7 = 0x0113
Convert the value to decimal and multiply by 0.25: 0x0113 = 275, 275 * 0.25 = 68.75dB

MANUAL IM672
Installation and Operation Page 14
4.5.6 UART Mode
UART mode is an asynchronous full-duplex serial interface consisting of two signals: RXD receive data in and TXD
transmit data out. This provides a logic-level "COM port" style interface that can be used directly with most serial
terminal emulators and control programs. The interface provides user-selectable standard baud rates from 9600 to
115200 (see SET BAUDRATE command) with a fixed data format of no parity, 8 data bits, 1 stop bit (N81).
This mode uses the same ASCII text-based messages and commands as the USB CDC interface.
4.6. AUX Application Modes
4.6.1 PIOSW Mode
PIOSW (PIO single-wire) is a special subset of PIO mode that enables the rapid switching of attenuation between
0dB and max attenuation using a single input bit D0 (Pin 1). In PIOSW mode setting D0=HIGH sets the attenuator
to its max dB value, while D0=LOW sets 0dB attenuation. RF ON/RF OFF switching rates in excess of 800 KHz are
supported.
RF OFF
(MAX dB)
RF ON
(0dB)
D0 = 0 D0 =1RF LEVEL
4.6.2 PULSE Mode
PULSE mode allows the UUT to generate a pattern of pulsed RF ON/RF OFF levels based on user settings. During
the RF ON time the attenuation is set to 0dB, and during the RF OFF time the attenuation will be set to the max
value. The programmable settings include the RF ON pulse width (PULSE WIDTH), time interval between pulses
(PULSE INTERVAL), the number of pulses in a group (PULSE COUNT), and the time interval between groups (PULSE
TIME). The pulse timing parameters have two ranges: 1-32000 usecs in 0.5 usec increments, and 1-64000 msecs
in 1 msec increments. Setting PULSE COUNT=0 will result in a continuous PULSE WIDTH/PULSE INTERVAL pattern,
disregarding the PULSE TIME setting. All PULSE parameters are programmed via USB commands and are stored in
NVM memory for standalone use.
When operating in PULSE mode the AUX interface connector provides two TTL digital signals used for control and
status: PULSE_ENA input (D0, Pin 1) and PULSE_STAT output (D2, Pin 3). When PULSE_ENA=HIGH pulse operation
is enabled, and PULSE_ENA=LOW sets pulse mode idle waiting for the enable signal to assert. The input pull-up
on the D0 pin can be used to supply a 1 if enable control is not required (see SET WPU), and is on by default. The
PULSE_STAT output will assert high when the RF output is on (0db) during any pulse operation, and will be low
otherwise.
In order to change operation, once the parameters are set via the SET PULSE commands you can switch from USB
to AUX mode using the command RUN AUX. The USB connection will be terminated and the 420X will reboot into
AUX PULSE mode. Using this method the PULSE_ENA pin changes function such that a low on PULSE_ENA will stop
pulses and return you to USB operation.

MANUAL IM672
Installation and Operation Page 15
INTERVAL
(RF OFF)
WIDTH
(RF ON)
RF LEVEL
COUNT = 3
TIME INTERVAL
(RF OFF)
WIDTH
(RF ON)
COUNT = 3
4.6.3 FADE Mode
FADE mode allows the UUT to generate an attenuation ramp RF signal. The programmable settings in this mode
include the start and stop attenuation values (FADE START/FADE STOP), the ramp increment value (FADE
STEPSIZE), the ramp update interval time (FADE INTERVAL), and dwell and pattern repeat times (FADE
DWELL/FADE TIME). In FADE mode the signal will ramp from START to STOP attenuation, wait the DWELL time,
ramp back from STOP to START attenuation, and then wait TIME before repeating the pattern. The START and
STOP attenuation values can be any settings valid for the attenuator, and the attenuation will ramp up or down as
required. All time parameters are specified in msec units, and both the DWELL and TIME can be set to 0 which will
result in a continuous ramp pattern with no delays. All FADE parameters are programmed via USB commands and
are stored in NVM memory for standalone use.
When operating in FADE mode the AUX interface connector provides two TTL digital signals used for control and
status: FADE_ENA input (D0, Pin 1) and FADE_STAT output (D2, Pin 3). When FADE_ENA=HIGH fading operation
is enabled, and FADE_ENA=LOW sets fade idle waiting for the enable signal to assert. The input pull-up on the D0
pin can be used to supply a 1 if enable control is not required (see SET WPU), and is on by default. The FADE_STAT
output will assert high when the RF output is ramping attenuation, and will be low otherwise.
In order to change operation, once the parameters are set via the SET FADE commands you can switch from USB
to AUX mode using the command RUN AUX. The USB connection will be terminated and the 420X will reboot into
AUX FADE mode. Using this method the FADE_ENA pin changes function such that a low on FADE_ENA will stop
fading and return you to USB operation.
INTERVAL
DWELL
TIME
STEPSIZE
START
STOP

MANUAL IM672
Installation and Operation Page 16
4.6.4 USB Mode AUX pin usage
When the 420X operates in USB mode, AUX connector J1 pin 8 (BOOTN) is used as a boot select pin. When power
is first applied via USB VBUS, the state of the BOOTN pin is checked. If BOOTN is a logic-low level then the
attenuator powers up as a USB HID device (USB VID=25EA, PID=003C) into a special bootloader mode that can
be used to download firmware updates. For normal USB operation leave the AUX pins unconnected. Consult with
the factory for more information on performing program updates.
4.6.5 USB
In USB mode the attenuator is controlled and powered via a standard USB 2.0 connection to a USB host. The 420X
operates as a USB CDC device (USB VID=25EA, PID=106D), so it may be controlled via any software that can
communicate to a standard virtual COM port. Programming is done via simple ASCII text-based message strings to
control the device (see the Command section later).
For ease of use, the 4 has two modes of operation: console and raw mode. Console mode provides a simple
command-line based interface that can be used in conjunction with any standard terminal emulator program.
Console mode sends command prompts ('>'), echoes received characters, issues error messages, and supports the
backspace key for simple editing, while raw mode is more suitable for programming. By default, the unit is shipped
with Console mode enabled, but this operation can be change by the user (see the CONSOLE command for more
details). A typical Console mode display is shown below:
API Weinschel 4205A USB Attn V1.40
firmware: 1012532301C
serialno: 0004A3DB4AE8
alias: 1234
RF config: 4205A-95.5, 95.75, 0.25, 300KHz-6GHz
>help
*CLS, *ESR?, *IDN?, *OPC?, *RST, *TST?, ERR?
ATTN db
ATTN?
STEPSIZE db
STEPSIZE?
INCR
DECR
FADE start stop interval
FADE? start stop interval
ALIAS?
ATTNIO [0-1023]
ATTNIO?
DELAY msec
REPEAT n
RFCONFIG?
CONSOLE [ENABLE|DISABLE|ON|OFF]
CONSOLE?

MANUAL IM672
Command Operation Page 17
SET AUX [PIO|SPI|I2C|UART|PIOSW|PULSE|FADE]
SET USB [CONNECT|PMT|RMT] val
SET [ALIAS|BAUDRATE|ATTN|I2CADDR|I2CTRIG|PINOUT|WPU] val
SET PULSE [WIDTH|INTERVAL|TIME] val[ms|us]
SET PULSE COUNT val
SET FADE [START|STOP|STEPSIZE|INTERVAL|DWELL|TIME]
SHOW [SET|VERSION]
FACTORY PRESET
SYSTEST [EXT|PIO|PIO?|XSUM]
REBOOT
RUN [AUX|LOADER]
5. Command Operation
Commands are comprised of text-based ASCII strings. The command parser is case-insensitive, so either upper or
lower case characters are acceptable. Command parameters may be separated with either an ASCII SPACE char
(0x20) or an ASCII COMMA char (0x2E), but the separator character used must be the same within an individual
command string. Additional SPACE characters are ignored. Input program messages may be terminated using either
an ASCII CR character (0x0D) or an ASCII LF character (0x0A). Command message strings are limited to 128
characters total, including the terminator. Multiple commands can be included in one message by separating the
individual commands with an ASCII SEMICOLON character ';' (0x3B), up to the 128 character message limit.
Typically, Response messages sent from the device are terminated using both a CR (0x0D) and LF (0x0A) to
terminate the message. The output terminator sequence may be changed using the RMT command. A list of
supported commands can be seen by typing 'HELP' at the Console prompt.
The command structure/operation is similar to that used in IEEE 488.2, and includes some of the 488.2 Common
Commands such as *IDN?, *RST, *CLS, and *OPC?, in addition to device specific commands. In 488.2,
programming commands take one of two forms: a Program message or a Query message. Program messages are
used to send commands to the device, while Query messages are used to elicit a response. Query commands are
those that contain a '?' character. In general, the device does not generate any response to a program message
unless the message contains a valid Query command. (Note that this does not apply when operating in Console
mode, or when using some commands such as HELP which are designed to provide the user general information).
You can use this feature to provide a method to synchronize command execution with the controller by appending
a Query to the desired command, and waiting for the response. For example, sending "*CLS;*OPC?" will place a
"1" in the output queue when the *CLS command has been executed. Query commands that return multiple values
will have the values separated by an ASCII COMMA character (0x2E). If multiple Query commands are included in
the same message, the individual query responses will be separated with an ASCII SEMICOLON character (0x3B).
Commands that loop or repeat (such as FADE and REPEAT) can be terminated by sending a BREAK condition, which
is supported in both USB and UART modes. For USB, a BREAK is defined by the CDC class SEND_BREAK request
code, while for UART mode a BREAK occurs when the sender's TX line is held at a logic 0 for longer than one frame
time (11 bits).
An Error Queue is provided that logs the results of command/execution errors in a FIFO fashion. The queue entries
can be read using the ERR? command, which returns both an error code and a descriptive text message, such as
101, "invalid command"
When the queue is empty, ERR? returns the message 0, "no error". The queue can be emptied by repeatedly
sending ERR? until all entries are read from the queue, or via sending the *CLS message.

MANUAL IM672
Command Operation Page 18
Unless otherwise specified, commands revert to their default setting at system reset/poweron, with the exception
of the system setup and configuration commands which store their setting in non-volatile memory (NVM).
5.1. Command Reference
In the command descriptions that follow, argument types are described using the following additional conventions
to indicate the relative size of the parameter:
Argument Type
Relative Size
Byte
Used to indicate an 8-bit unsigned integer
Word
Used to indicate a 16-bit unsigned integer
Int8
8-bit integer
Int16
16-bit integer
Int32
32-bit integer
String
Character data, including the max number of characters allowable. (ie string8 has a max
of 8 chars)
Numeric arguments default to decimal (base 10) notation, but may optionally be provided in hex if appropriate by
using a "0x" prefix (ie 0x0A = 10 dec)
Required command keywords are shown in CAPITAL letters, and arguments are shown in italics . Square brackets
'[]' may be used to indicate a selection or optional parameter, for example [ select ]. Optional parameters, if not
supplied by the user, assume the default setting specified in the text.
5.2. Application Specific Commands
Attenuation value settings are specified in dB, with up to 2 digits of precision after the decimal point for attenuators
that support step sizes of < 1dB. When specifying integral dB values, usage of the decimal point format is strictly
option (ie '10' is the same as '10.0'). The attenuation setting must be a multiple of the attenuators intrinsic step
size or the command will generate an error. For example, an attenuator that has a stepsize of 0.25 dB will accept
settings of 0.25, but will generate an error if set to 0.3. For responses, attenuation values will be formatted to the
base precision of the attenuator.
Attenuation switching speed requirements are built into the command execution time and are always enforced such
that if you execute a command sequence such as "ATTN 10;*OPC?" the response will not be sent until the
attenuator has been programmed and has changed state. The attenuator can be switched at the maximum rate
that commands are executed, which is typically in the 1-2ms range.
ATTN
Function: set attenuator
Syntax: ATTN setting
Argument(s): setting attenuator setting, in dB. s etting =0-max attenuation value, or MAX
Remarks: This command sets the RF attenuator to the dB value provided by setting . If setting is MAX, then
the maximum dB value for that attenuator will be used.
Return Value: none
Example(s):
ATTN 10 // sets attn to 10 dB
ATTN MAX // sets attn to max
ATTN 15.25 // sets attn to 15.25 dB

MANUAL IM672
Command Operation Page 19
ATTN?
Function: read attenuator setting
Syntax: ATTN?
Argument(s): none
Remarks: This command returns the current setting of the attenuator
Return Value: attenuator setting, in dB
Example(s):
ATTN 10 // sets attn to 10 dB
ATTN? // read attn setting
10.00 // returns attn setting (10 dB)
STEPSIZE
Function: set attenuator stepsize
Syntax: STEPSIZE setting
Argument(s): setting attenuator stepsize, in dB. setting =0-max attenuation value
Remarks: This command sets the attenuation stepsize. This command can be used with the INCR, DECR,
and FADE commands to change the step value. Specifying a setting of 0 sets the stepsize to the
intrinsic step value for the attenuator, in effect removing any previous STEPSIZE command.
Return Value: none
Example(s):
STEPSIZE 10 // sets attn stepsize to 10dB
STEPSIZE 0 // sets the stepsize back to native value (ie 0.25dB)
STEPSIZE?
Function: read attenuator stepsize setting
Syntax: STEPSIZE?
Argument(s): none
Remarks: This command returns the current stepsize
Return Value: attenuator setting, in dB
Example(s):
STEPSIZE 10 // sets attn stepsize to 10dB
STEPSIZE? // read attn stepsize setting
10.00 // returns attn stepsize (10dB)
INCR
Function: increment attenuator setting
Syntax: INCR
Argument(s): none
Remarks: This command increments the current setting of the attenuator by the STEPSIZE setting.
Return Value: none
Example(s):
ATTN 5 // sets attn to 5dB
STEPSIZE 10 // sets attn stepsize to 10dB
INCR // increments attn by current stepsize (5dB + 10dB = 15dB)
DECR
Function: decrement attenuator setting
Syntax: DECR
Argument(s): none
Remarks: This command decrements the current setting of the attenuator by the STEPSIZE setting.
Return Value: none
Example(s):
ATTN 15 // sets attn to 15dB

MANUAL IM672
Command Operation Page 20
STEPSIZE 10 // sets attn stepsize to 10dB
DECR // decrements attn by current stepsize (15dB - 10dB = 5dB)
FADE
FADE?
Function: fade attenuation value over time
Syntax: FADE start end interval
FADE? start end interval
Argument(s): start initial attenuation setting
end final attenuation setting
interval time per attn increment, in msec (1-60000)
Remarks: This command ramps the attenuation value at a user specified rate. The start and end dB values
can be any settings valid for the attenuator, and the attenuation will ramp up or down as required.
The attenuation value will step according to the current STEPSIZE setting. Attenuation values are
changed at the rate specified by interval, which is in units of msec. Note that no other commands
can be executed until the fade operation is completed, but the operation can be terminated via a
BREAK condition. The query form of the command (FADE?) will return the current attenuation
values as the steps are executed. Note: This command does not affect the AUX FADE mode
settings.
Return Value: none
Example(s):
STEPSIZE 1.0 // set stepsize to 1 dB
FADE 10 85 500 // fade from 10dB to 85dB at a rate of 500ms
STEPSIZE 0 // set stepsize to default (0.25dB)
FADE? 90 0 1000 // fade from 90dB to 0dB in 0.25dB steps at 1000ms (1sec)
90.00 // values are sent as the attenuation changes
89.75
……
0.25
0.00
5.3. 488.2 Common Commands
*CLS
Function: clears the error status
Syntax: *CLS
Argument(s): none
Remarks: This function clears the Error Queue
Return Value: none
Example(s):
*CLS
*IDN?
Function: Reads the system identification information
Syntax: *IDN?
Argument(s): none
Remarks: This function is used to read the system identification info, which is a string consisting of the
following data: manufacturer, model, serial number, and firmware version.
Return Value: idstr string id info
Example(s):
*IDN?
API Weinschel, 4205A, 0004A3DB3013, V1.40