SEKONIC PR Wireless System TX Module

Safety Instructions
RADIO TRANSMITTER PRODUCT
This product emission Radio-Frequency energy. Be carefully to integrate your system. Make sure to be taken to cautions and specifications in this manual, especially operation environment for best performance. Must not exceed supply voltage limit, or may be damaged permanently. This Product conforms to world-wide ISM-standard radio-regulations, so you may operate according to your local regulations. ISM-band device operate in shared frequency with others, so Interference can’t be ruled out.
SAFETY PRECAUTIONS!
- Do not attempt to operate the equipment before studying the instruction manual and the accompanying safety instructions. Failure to do so may result in serious injuries.
- Make sure that Safety Instructions is always accompanied the equipment!
- This products are intended for professional use!
- Do not place or use the equipment where it con be exposed to moisture, extreme electromagnetic fields, or in areas with flammable gases or dust!
- Do not expose the equipment to rapid temperature changes in humidity conditions as this could lead to water condensation in the unit.
- Equipment must only be serviced by authorized and competent service personnel!
- Any modification will break the modular certification and require the module to be re-certified.
FINAL DISPOSAL
- This equipment contains electrical and electronic components that could be harmful to the environment.
- Follow local requirements for separate disposal of waste, for instance WEEE directive for electrical and electronic equipment on the European market, when the product’s life has ended.
Introduction
- WS TX-Module is wireless transmit function module, using 2.4GHz ISM-band.
- It is designed to integration with SEKONIC Exposure-meter/Color-meter products, Use remote-control for professional photography lighting equipment.
- Radio control range performance is up to over 50m, in open-space.
- WS TX-Module ‘Model PR’ is compatible with “Profoton Air1/Air2 system”, under agreement of SEKONIC-Profoto collaboration.
General Description
- WS TX-Module Model PR is using Texas Instruments CC2500 high performance
- RF-Transceiver chip with +10dBm power amp, and controller core (MCU) is a 16-bit renesas microprocessor, with integrated (on-board pattern) Antenna, and function-feature set is compatible with Profoto-Air radio system.
- Host Interface is a 3V-UART communication and simple TRIGGER-SW input.
System Diagram

Hardware Description
Dimensions
- Outer cover 34.0 x 27.7 x 11.5 mm +/- 0.5mm [Width,Length,Height]
- Weight : approx. 8g
- Internal circuit board 29 x 25 x 6 mm +/- 0.5mm [Width,Length,Height]
Weight : approx. 8g
Product Image

Circuit board assy .Mechanical Drawing

Electrical Characteristics
HOST Interface
| Pin | Function | |
| 1 | Vcc | DC Power |
| 2 | (SYNC_OUT) | Connected to GND Internally |
| 3 | SYNC_IN | TRIGGER Input (Active L) |
| 4 | TX_Complete | Status Output (Active L) |
| 5 | READY | Status Output (Active L) |
| 6 | CTS | Status Output (Active L) |
| 7 | TXD | UART TxD (Output) |
| 8 | RXD | UART RxD (Input) |
| 9 | RESET | RESET INPUT (Active L) |
| 10 | GND | |
| 11 | (reserved) | Keep open (not to connect) |
| 12 | GND |
Interface Description
- The interface to the host-system is implemented as a 12 pin male connector.
- Connector part is JC HSW2W-S12G, recommended matching pin-header is IK210W39-S12G-H1.5(or compatible 2.00mm pith, 3.9mm-height square-pin type header pin.)
UART Serial Interface
- The UART is using pins 7,8. Signal level is 3V-CMOS level, these signals can directly connect to host MCU. If you wish to connect to RS232 line, must use a
- TTL(CMOS) level converter (like a FTDI converter dongle).
- Serial characteristics : 38400, 8, N, 1 (no flow control) [ firmware for L-858 Installation ]
- Connecting the module to an RS232 line without a level converter may cause permanent damage to the module.
- For available command list and control session sequences, please refer to the
- Control Command Spec documentation.
RESET Interface
- RESET Interface forces control MCU to hardware-reset (active low, minimum 10uS).
- The following conditions also reset on the module (MCU).
- Power on reset
- Low voltage (Brown Out) detected from internal MCU supervisory function.
- Reset by Software (command)
Operating Conditions
| Parameter | Min | Max | Unit |
| DC Supply | 2.7 | 3.3 | V |
| Current | 0.1 | A | |
| Temperature | -10 | 50 | ℃ |
| Humidity | 95 | % RH |
Radio Characteristics
| Parameter | Min | Typ. | Max | Unit |
| Frequency Range | 2403.9986 | 2479.3136 | MHz | |
| Channel Step | 0.33325 xN | MHz | ||
| Frequency Stability | -96 | +96 | kHz | |
| Transmit Power | 4.5 | 6.0 | 7.5 | dBm |
| Antenna(Integrated)
Gain |
0 | dBi |
The module have operation feature compatible to “Profoto Air1, Air2 Protocol”.
The feature set is commonly based on, Texsas Instrument proprietary packet,
Air-interface Detail definitions is as follows
| Parameter | Profoto Ai1,Air2 protocol specification | ||
| Modulation | MSK | ||
| RF Chip Mode | Texas Instruments proprietary frame | ||
| Frequency Channel (Channel-ID:Physical ch. mapping) | 1 : 2403.9986 11:2432.9916
2 : 2411.9967 12:2435.9908 3 : 2416.9955 13:2438.9901 4 : 2421.9943 14:2451.3204 5 : 2426.9930 15:2456.6524 6 : 2446.9882 16:2459.6517 7 : 2453.9864 17:2462.3177 8 : 2479.3136 18:2465.3170 9 : 2406.9979 19:2468.3162 10:2429.9923 20:2471.3155 |
MHz | |
| Grouping | Logical-sub Grouping in Standard frame header | ||
| Data Rate | 500 kbps | ||
More detail information of operation mode, please refer to command reference documentation
Internal mechanism
Boot-up
This module is originally intended to integration with L-878 Light meter product.
As of nature, if the module is cold-started (or hardware reset), the module firmware initialize internal resources. After complete initialize, send boot-up message to host on UART interface. Boot-Up message contains Module ID, hardware and firmware revision code and serial number.
Idle-state
After boot-up state, the module enter to idle-state. In idle state, the module firmware wait a command from host or TRIGGER signal. If no host command/TRIGGER Input for 10mS-duration, the module firmware go into Sleep State (HALT State).
Sleep-state
In the Sleep state, the module control-MCU is in HALT State.
So the module firmware cannot run until an interruption is occur. (TRIGGER or UART)
TRIGGER-Operation
- The module can get TRIGGER Input signal from host in any state, include HALT state.
- TRIGGER Input (SYNC-IN) signal can acknowledged, minimum 10uS duration low-level.
- After TRIGGER Input is acknowledged, module firmware send a radio packet, ‘RFTrigger- Command’. ‘RF-Trigger Command’ frame, defined by target feature set (air-interface), is to trigger Strobo-flash(s).
- TRIGGER Input is must not allowed continuously low state. To be lesser to 1mS-Low.
- If no other input-low after process-complete, the module firmware go into idle state.
Command-Operation
- The module can get UART Command from host in any state, include HALT state.
- The module firmware validate the received command, and process the command. eg. Send a command on radio/ status report/ RF-mode control (change)
- If no other command after process one command, the module firmware go into idle state.
Send a radio packet state
- In send a radio packet state, the module send a packet-frame, frame content is defined by feature set.
- After complete send-operation, the module enters idle state.
Integration (Installation)
- WS TX-Module is designed for installation to L-878 Light Meter Product.
- So, this product’s Casing (outer cover) is drop-in fit to Light Meter’s dedicated install position. [ RF TX Module Interface ]
- L-878 Light Meter (back-side, battery cover removed)

Radio Certification
World-wide Usage of Radio Spectrum Regulation
WS-TX-Module Model PR operates on the license-free 2.4GHz ISM Band
(Short Range Devices).
This band may be used in most part of the world. Regional restrictions may apply in most countries/region.
NOTE!
Refer to national regulations for the region where the WS-TX-Module shall be oper ated and make sure that they are followed.
Europe
- WS-TX-Module Model PR has been tested to EU Directive assessed radio module, that is CE marked and has been manufactured and tested with intention of
- being integrated into a final product.
- The module has been tested to EU Directive 2014/53/EU Essential Requirements for Health and Safety(Article(3.1(a)),and Radio(Article3.2) .
- Harmonized standards applied:
- Air Interface of the radio systems pursuant to article 3(2)
- EN 300 440 v2.1.1(2017 01)
- Safety requirements concerning human exposure to electromagnetic compatibility according to article 3(1)a: EN 62479
The manufacturer must maintain a copy of the module documentation and ensure the final product does not exceed the specified power ratings, antenna specifications, and/ or installation requirements as specified in the user manual. All test reports are available, please contact our sales stuff.
- The “CE” marking must be affixed to a visible location on the OEM product.
The CE mark shall consist of the initials “CE” taking to following form: - If the CE marking is reduced or enlarged, the proportions given the above graduated drawing must be respected.
- The CE marking must have a height of at least 5mm except where this is n ot possible on account of the nature of the apparatus.
- The CE marking must be affixed visibly, legibly, and indelibly.
- More detailed information about CE marking requirements you can find at “DERECTIVE 1999/5/EC OF THE EUROPEAN PARLIAMENT AND THE COUNCIL” on March 1999 at section 12.
Once approved and CE marked, the system may be sold and used EU/EEC countries without the need to have country-specific approval tests
United States and Canada
FCC and ISED Canada
Compliance Statement (Part 15.19)
This device complies with Part 15 of FCC rules and RSS Gen/RSS-210 of industry Canada.
Operation is subject to the following two conditions:
- This device may not cause harmful interference and,
- This device must accept any interference received, including interference that may cause undesired operation .
Warning (Part15.21)
Changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment .
RF exposure compliance
- To comply with FCC/ISED RF exposure compliance requirements, a separation distance of al least 20 cm must be maintained between the antenna of this device and all persons.
- This transmitter must not be co-located or operation in conjunction with any other antenna or transmitter .
Requirement to end product
This module must be integrated only by OEM integrators under the following conditions.
- General Restriction
OEM integrator has to be aware not provide information to the users regarding how to install or remove this module in the Users Manual of the end product which integrate this module. Installation by end users is strictly prohibited. - Antenna
OEM Integrator shall use this module without any modifications including antenna.
OEM Integrator must make sure that 20cm minimum separation is maintained between users and the antenna. - Co-location
This module must not be co-located in conjunction with any other antenna or transmitter. The module integrator shall obtain FCC approval for the end produ ct, if the module is used for co-location operation. - Markings
To satisfy FCC/ISED exterior labeling requirements, the following text must be places on the exterior of the end product.
Contains Module FCC ID: PFK-TXMPR, ISED:3916A-TXMPR
Any similar wording that expresses the same meaning may be used.
If Host device in which is integrated this module, has a built-in display
NOTE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:
- Reorient or relocate the receiving antenna.
- Increase the separation between the equipment and receiver.
- Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
- Consult the dealer or an experienced radio/TV technician for help.
Change History
| Revision | Date | Description / Changes , | Page(s) |
|
0.1 |
2025.07.28 | Initial release. |
Total 14 |
|
0.2 |
2026.05.13 | add casing definitions, mechanical dementions, installation image updated. | |
- Fukushima Development Office.
- Development division, SEKONIC Corporation .
- Fushi-o-gami 27-1, Fukushima-shi, Fukusima-Pref. 960-8154, JAPAN
- TEL 8124-545-2237
- FAX 8124-545-2491
- Company Web-site http://www.sekonic.co.jp
Documents / Resources
![]() | PR Wireless System TX Module |
References
- fcc.gov/oet/info/rules/www.fcc.gov
- sekonic.co.jpwww.sekonic.co.jp
- User Manualmanual.tools
