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Electronic Focus Accessory (EFA) Kit

SKU# 240901

Price: $800.00

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  • The EFA kit automates focusing on the optional Hedrick Focuser, or IRF90 rotating focuser.
  • Monitors temperature (primary-mirror and OTA back-plate).
  • Controls the fans built-in to CDK telescopes.
  • Ensure you have the proper EFA kit selected for your telescope below.
    • 125901-Kit is for CDK12.5 OTAs.
    • 240901-Kit is for CDK14, CDK17, CDK20, and CDK24 OTAs.

Description

Description

The EFA control box can be mounted to the back plate of any PlaneWave telescope OTA (12.5 through 24 inches).  The EFA Kit plugs into the temperature sensors and fan control systems that are built into each telescope. A Hand Control is provided to control an optional Focuser or Rotator when standing at the eyepiece.  The EFA kit comes with PlaneWave Interface (PWI3), a software package that controls all EFA functions from a PC.  Cables and adapters are provided to attach the EFA kit to a PC. The EFA kit is ASCOM compatible.

Specifications

Specifications

EFA PC Port Protocol Overview

  • Message Packet:
    • SOM Start Of Message byte must start every message packet.   SOM = 59 = 0x3B
    • NUM   Number of Bytes is calculated by: NUM = [(Packet Byte Count) – 3]   (Note: The bytes SOM, NUM, and CHK are not counted in NUM)
    • SRC   Source Address
    • RCV   Receiver Address
    • CMD   Command   See below for a list.
    • DA1   DATA1   Optional data byte, Some commands require data.
    • DA2   DATA2   Optional data byte, Some commands require data.
    • DA3   DATA3   Optional data byte, Some commands require data.
    • CHK   Checksum   The last byte of the message packet is a Checksum. It is calculated by summing the bytes of the packet, excluding the SOM and CHK, and taking the Least Significant Byte of the two’s complement. Examples are below.
  • When data bytes combine to represent an integer, the MOST-SIGNIFICANT data byte is sent first.
  • All messages require the Receiver to respond. If the no data response is necessary, the Receiver will responsd by sending a meesage with the CMD it received.   NOTE: THE EFA RESPONDS TO ANY MESSAGE RECEIVED, EVEN INVALID COMMANDS!
  • Port Settings:
    • Baud Rate: 19200
    • Parity: None
    • Data bits: 8
    • Stop bits: 1
    • RTS/CTS Flow Control
      • PC waits for the CTS to be clear
      • PC enables the RTS
      • PC sends message packet
      • PC clears the RTS

Focuser

  • Scale Factor: (115134.42 Encoder Counts) = (1 mm Focuser Travel)
  • Nominal Focuser Travel: 33 mm = 3799422 Encoder Counts
  • Focuser Encoder = 0 when racked completely in

Standard Addresses

DeviceDecimalHex
PCComputer320x20
HCHand Control140x0D
FOCFocuser180x12
FANFan Controller190x13
TEMPTemperature Sensor180x12

Commands

CommandDescriptionCMD (Hex)Send DataResponse DataSend Sample (Hex)Respond Sample (Hex)
MTR_GET_POSGet position0x013 bytes (encoder position)3B 03 20 12 01 CA3B 06 12 20 01 00 00 00 C7

Encoder Position = 0

MTR_GOTO_POS2GOTO position0x173 bytes (encoder position)1 byte (1=OK)Goto Position = 0x140000 = 1310720
MTR_OFFSET_CNTSet current focuser encoder position. Often used to set focuser encoder to Zero.0x043 bytes (encoder position)1 byte (1=OK)3B 06 20 12 04 14 00 00 B0

Set Encoder Position = 0x140000 = 1310720

3B 04 12 20 04 01 C5
MTR_GOTO_OVERDetermine if the motor is moving during a GOTO?0x131 byte (255=YES, 0=NO)3B 03 20 12 13 B83B 04 12 20 13 FF B8

Goto is Over

MTR_SLEWLIMITMAXSet the Maximum Slew Limit.0x1B3 bytes1 byte (1=OK)3B 06 20 12 1B 3B 82 60 90

Set Min Slew Limit = 0x3B8260 = 3900000

3B 04 12 20 1B 01 AE
MTR_SLEWLIMITGETMAXReturns the Maximum Slew Limit in encoder ticks0x1D3 bytes (encoder position)3B 03 20 12 1D AE3B 06 12 20 1D 3A 4F A5 7D

Maximum Slew Limit = 0x3A4FA5 = 3821477

MTR_PMSLEW_RATEMove the motor positive. Motor will stop when the Max Slew Limit is reached.0x24One byte for the speed (stop to fastest) = (0x00 to 0x09)1 byte (1=OK)3B 04 20 12 24 09 9D

Go Positive Top Speed

3B 04 12 20 24 01 A5
MTR_NMSLEW_RATEMove the motor negative. Motor will stop when the Min Slew Limit is reached.0x25One byte for the speed (stop to fastest) = (0x00 to 0x09)1 byte (1=OK)3B 04 20 12 25 09 9C

Go Negative Top Speed

3B 04 12 20 25 01 A4
TEMP_GETGet the temperature of one sensor0x26One byte address(Primary=0, Ambient=1, Secondary=2)3 bytes (byte1=address, [byte2 & byte3] = Temperature…See Formula Below)3B 04 20 12 26 01 A3

Request Temp for ambient

3B 05 12 20 26 5C 01 46

Temp=5C01 (see below for conversion to Celcius)

FANS_SETSet the fans, on or off.0x271 byte (1=ON, 0=OFF)1 byte (1=OK)3B 04 20 13 27 01 A1

Set FANS=ON

3B 04 13 20 27 01 A1
FANS_GETGet the fans state, on or off.0x281 byte (0=ON, 3=OFF)3B 03 20 13 28 A23B 04 13 20 28 00 A1

FANS=ON

MTR_GET_CALIBRATION_STATEDetermine if the focuser as been calibrated. Useful for Handcontrol and PWI Focus software.0x301 byte (0x40)1 byte (0=NO, 1=YES)3B 04 20 12 30 40 5A3B 04 12 20 30 01 99

Motor = calibrated.

MTR_SET_CALIBRATION_STATESet the calibration state for the focuser. Useful for Handcontrol and PWI Focus software.0x312 bytes (Calibrated = 40 01) and (Not = 40 0)1 byte (1=OK)3B 05 20 12 31 40 01 57

Set calibration = true

3B 04 12 20 31 01 98
MTR_GET_STOP_DETECTDetermine if Motor will stop when the focuser hits a physical hardstop.0xEE1 byte (1=YES, 0=NO)3B 03 20 12 EE DD3B 04 12 20 EE 01 DB

Stop Detect = enabled

MTR_STOP_DETECTSet the controller to stop when focuser hits a physical hardstop.0xEF1 byte (1=YES, 0=NO)3B 04 20 12 EF 01 DA

Set Stop Detect = enabled

3B 03 12 20 EF DC
MTR_GET_APPROACH_DIRECTIONGet the approach of motor during a goto0xFC1 byte (0=negative, 1=positive=default)3B 03 20 12 FC CF3B 04 12 20 FC 00 CE

Motor is set to approach from positive, this is default.

MTR_APPROACH_DIRECTIONGet the approach of motor during a goto0xFD1 byte (0=negative, 1=positive=default)1 byte (1=OK)3B 04 20 12 FD 00 CD

Set APPROACH = positive, this is default.

3B 04 12 20 FD 01 CC
GET_VERSIONGet Firmware Version0xFE2 bytes (byte1=Major, second byte2=minor)3B 03 20 12 FE CD3B 05 12 20 FE 01 05 C5

Version = 1.5

Convert Temperature to Celsius

  • The response request for temperature is 3 bytes
  • byte1=address, byte2 & byte3 are used to calcuate the temperature
  • If there is no sensor for the address requested, the response bytes are 0x7F7F
  • (Primary=0, Ambient=1, Secondary=2)

Conversion of the two received bytes to Celsius

int rawTemp = byte2*256 + byte3
bool tempIsNeg = false
if(rawTemp > 32768)
{
tempIsNeg = true
rawTemp = 65536 – rawTemp
}
int intPart = RawTemp / 16
int fractionDigit = (RawTemp – intPart) * 625 / 1000
float celciusTemp = intPart + fractionDigit / 10
if(tempIsNeg) celciusTemp = -celciusTemp

PC Port Cable – RJ45 and DB9

  • 2 Receive Data
  • 3 Transmit Data
  • 5 Signal Ground
  • 7 Request To Send
  • 8 Clear To Send

Downloads

Downloads

PlaneWave Interface 3.5.2 12.24 MB 7462 downloads

Latest stable release

PWI Focus 1.0.20 2.56 MB 7465 downloads

PWI Focus is used on legacy systems where the PC connects to the EFA through a Celestron-branded hand controller.

ASCOM Driver for PWI Focus 525.64 KB 5951 downloads

ASCOM Driver for PWI Focus

PlaneWave AutoFocus COM Interface 13.56 KB 151 downloads

PlaneWave AutoFocus COM Interface ...