Fohhn-Net protocol documentation - © Fohhn Audio AG - 15.04.20111 / 8
Fohhn-Net protocol
Fohhn-Net is based on EIA-485 (formerly RS-485), thus you
need a device with a EIA-485 / RS-485 interface to connect to
Fohhn-Net devices.
With the optional NA-3 ethernet adapter it is possible to send
the data as a UDP package. The NA-3 is a bridge between
ethernet and EIA-485 for the Fohhn-Net protocol.
Signal RJ-45 XLR
Shield / GND Shield Pin 1
DATA + Pin 3 + Pin 6 Pin 2
DATA - Pin 4 + Pin 5 Pin 3
Fohhn-Net uses a half-duplex 2-wire connection.
Most of the Fohhn-Net devices have RJ-45 or terminal
blocks as interface socket.
Optional XLR cabeling is possible, with adapter cables.
Serial parameters:
19200 baud
1 startbit
8 databits
1 stopbit
IP based communication (with NA-3 adapter, only):
Protocol: UDP
Port: 2101
You have to send the same binary data as a UDP package to
the IP address of the NA-3 and UDP port 2021.
The NA-3 adapter transfers the data over its EIA-485 port to the
Fohhn-Net devices.
The NA-3 adapter sends the reply from the Fohhn-Net device
as a UDP package to the source ip address and source port of
the last request.
all other pins on the RJ-45 connector have not to be connected !
Possible cable types are:
- CAT5, CAT6 or CAT7 cable
- 2 x 2 x 0.6mm-0.8mm (J-Y(ST)Y 2x2x0.6)
- microphone cable
Fohhn-Net protocol documentation - © Fohhn Audio AG - 15.04.20112 / 8
Fohhn-Net protocol
Protocol encoding
The Fohhn-Net protocol has a startbyte <SB>
and a controlbyte <CB>.
The startbyte <SB> or the controlbyte <CB> must
never occur in the message.
If the data (every byte, except the startbyte)
contains the value of startbyte or controlbyte it
must be encoded with the controlbyte <CB>
0xF0 = startbyte <SB>
0xFF = controlbyte <CB>
Encoding:
If the values from <SB> and <CB> are needed in
real data, you have to encode them with two
bytes
<CB> + 0x00 = 0xF0
<CB> + 0x01 = 0xFF
The controlbyte is not counted as a extra byte in
databyte count
Fohhn-Net protocol
Master sends
1. Byte Startbyte <SB>
2. Byte Device Address <ADDR>
3. Byte Databyte Count <COUNT>
4. Byte Command Byte <CMD>
5. Byte Addr MSB <ADDR_MSB>
6. Byte Addr LSB <ADDR_LSB>
7. Byte Databyte 1 <DATA> (min. one databyte)
N. Bytes Optional <DATA>
Slave acknowledge (timeout 330 ms)
N data bytes <DATA> (optional)
N+1 Byte Device Address <ADDR>
N+2 Byte Startbyte <SB>
Fohhn-Net protocol documentation - © Fohhn Audio AG - 15.04.20113 / 8
Loading a preset
Example: load preset 20 - 24 for device 1
Preset 20: 0xF0 0x01 0x01 0x05 0x01 0x14 0x00
Preset 21: 0xF0 0x01 0x01 0x05 0x01 0x15 0x00
Preset 22: 0xF0 0x01 0x01 0x05 0x01 0x16 0x00
Preset 23: 0xF0 0x01 0x01 0x05 0x01 0x17 0x00
Preset 24: 0xF0 0x01 0x01 0x05 0x01 0x18 0x00
Master sends
1. Byte Startbyte 0xF0
2. Byte Device Address 0x01 .. 0xFE
3. Byte Databyte Count 0x01
4. Byte Command Byte 0x05 // command LoadPreset
5. Byte ADR_MSB 0x01
6. Byte ADR_LSB 0x01 .. 0x64 // preset nr.
7. Byte Databyte 1 0x00
Acknowledge from Fohhn Audio DSP (slave)
1. Byte Device Address 0x01 .. 0xFE
2. Byte Startbyte 0xF0 // end of reply
Example: load preset 20 - 24 for device 2
Preset 20: 0xF0 0x02 0x01 0x05 0x01 0x14 0x00
Preset 21: 0xF0 0x02 0x01 0x05 0x01 0x15 0x00
Preset 22: 0xF0 0x02 0x01 0x05 0x01 0x16 0x00
Preset 23: 0xF0 0x02 0x01 0x05 0x01 0x17 0x00
Preset 24: 0xF0 0x02 0x01 0x05 0x01 0x18 0x00
Fohhn-Net protocol documentation - © Fohhn Audio AG - 15.04.20114 / 8
Set absolute volume
Master sends
1. Byte Startbyte 0xF0
2. Byte Device Address 0x01 .. 0xFE
3. Byte Databyte Count 0x03
4. Byte Command Byte 0x87 // command SetVolume
5. Byte Channels 0xXX // channels
6. Byte Index 0x01
7. Byte Volume_H 0xXX // volume
8. Byte Volume_L 0xXX // volume
9. Byte Flags 0xXX // flags
Acknowledge from Fohhn Audio DSP (slave)
1. Byte Device Address 0x01 .. 0xFE
2. Byte Startbyte 0xF0 // end of reply
Example: set volume for device 1, channel 1 + channel 2
0.0dB On: 0xF0 0x01 0x03 0x87 0x03 0x01 0x00 0x00 0x01
0.0dB Mute: 0xF0 0x01 0x03 0x87 0x03 0x01 0x00 0x00 0x00
-7.5dB On: 0xF0 0x01 0x03 0x87 0x03 0x01 0xFF 0x01 0xB5 0x01
+6.0dB On: 0xF0 0x01 0x03 0x87 0x03 0x01 0x00 0x3C 0x01
-40.0dB On: 0xF0 0x01 0x03 0x87 0x03 0x01 0xFE 0x70 0x01
*
*encoding of 0xFF
Notes
You can set multiple channels with one command.
Each channel has a value:
Channel 1: 0x01
Channel 2: 0x02
Channel 3: 0x04
Channel 4: 0x08
Channel 5: 0x10
Channel 6: 0x20
Examples:
For channel 1 and 2, this is 0x03
For all channels 1 to 6, the value is 0x3F
The volume is a 16-bit signed value. (value * 10)
For example:
+6.0dB has the value 60, in hex 0x003C
Volume_H: 0x00 and Volume_L: 0x3C
-40.0dB has the value -400, in hex 0xFE70
Volume_H: 0xFE and Volume_L: 0x70
Flags 0x01 is on, 0x00 mute.
Fohhn-Net protocol documentation - © Fohhn Audio AG - 15.04.20115 / 8
Set relative volume / mute
Master sends
1. Byte Startbyte 0xF0
2. Byte Device Address 0x01 .. 0xFE
3. Byte Databyte Count 0x03
4. Byte Command Byte 0x96 // command SetVolumeRelative
5. Byte Channels 0xXX // channels
6. Byte Index 0x01
7. Byte Volume_H 0xXX // volume
8. Byte Volume_L 0xXX // volume
9. Byte Flags 0xXX // flags
Acknowledge from Fohhn Audio DSP (slave)
1. Byte Device Address 0x01 .. 0xFE
2. Byte Startbyte 0xF0 // end of reply
Example: relative volume change for device 1, channel 1 + channel 2
-1.0dB On: 0xF0 0x01 0x03 0x96 0x03 0x01 0xFF 0x01 0xF6 0x01
+1.0dB On: 0xF0 0x01 0x03 0x96 0x03 0x01 0x00 0x0A 0x01
*
*encoding of 0xFF
Notes
You can set multiple channels with one command.
Each channel has a value:
Channel 1: 0x01
Channel 2: 0x02
Channel 3: 0x04
Channel 4: 0x08
Channel 5: 0x10
Channel 6: 0x20
Examples:
For channel 1 and 2, this is 0x03
For all channels 1 to 6, the value is 0x3F
The volume is a 16-bit signed value. (value * 10)
Flags 0x01 is on, 0x00 mute
0x05 is switch on (unmute)
If you send 0x01, the channels stay on - but they will
not unmute if they are muted.
For unmute send 0x05
Example: output mute for device 1, channel 1 + channel 2
On (Unmute): 0xF0 0x01 0x03 0x96 0x03 0x01 0x00 0x00 0x05
Off (Mute): 0xF0 0x01 0x03 0x96 0x03 0x01 0x00 0x00 0x00
Fohhn-Net protocol documentation - © Fohhn Audio AG - 15.04.20116 / 8
Set Routing
Master sends
1. Byte Startbyte 0xF0
2. Byte Device Address 0x01 .. 0xFE
3. Byte Databyte Count 0x03
4. Byte Command Byte 0x81 // command SetRouting
5. Byte Channels 0xXX // output channels
6. Byte Index 0x0X // input channel
7. Byte Volume_H 0xXX // gain
8. Byte Volume_L 0xXX // gain
9. Byte Flags 0xXX // flags
Acknowledge from Fohhn Audio DSP (slave)
1. Byte Device Address 0x01 .. 0xFE
2. Byte Startbyte 0xF0 // end of reply
Example: set routing for device 1, output channel 1
Input 1 0.0dB On: 0xF0 0x01 0x03 0x81 0x01 0x01 0x00 0x00 0x01
Input 3 0.0dB On: 0xF0 0x01 0x03 0x81 0x01 0x03 0x00 0x00 0x01
Input 1 0.0dB Off: 0xF0 0x01 0x03 0x81 0x01 0x01 0x00 0x00 0x00
Input 3 0.0dB Off: 0xF0 0x01 0x03 0x81 0x01 0x03 0x00 0x00 0x00
Notes
You can set multiple output channels with one command.
Each output channel has a value:
Output channel 1: 0x01
Output channel 2: 0x02
Output channel 3: 0x04
Output channel 4: 0x08
Output channel 5: 0x10
Output channel 6: 0x20
Examples:
For channel 1 and 2, this is 0x03
For all channels 1 to 6, the value is 0x3F
You can set one input channel with one command, only.
Input channel 1: 0x01
Input channel 2: 0x02
Input channel 3: 0x03
Input channel 4: 0x04
Input channels can not be combined.
The gain is a 16-bit signed value. (value * 10)
Flags 0x01 is on, 0x00 mute.
Fohhn-Net protocol documentation - © Fohhn Audio AG - 15.04.20117 / 8
Set Standby
Example: standby for device 1
Standby: 0xF0 0x01 0x01 0x0C 0x01 0x00 0x01
On: 0xF0 0x01 0x01 0x0C 0x01 0x00 0x00
Master sends
1. Byte Startbyte 0xF0
2. Byte Device Address 0x01 .. 0xFE
3. Byte Databyte Count 0x01
4. Byte Command Byte 0x0C // command SetStandby
5. Byte ADR_MSB 0x01
6. Byte ADR_LSB 0x00
7. Byte Databyte 1 0x0X // Standby
Acknowledge from Fohhn Audio DSP (slave)
1. Byte Device Address 0x01 .. 0xFE
2. Byte Startbyte 0xF0 // end of reply
Fohhn-Net protocol documentation - © Fohhn Audio AG - 15.04.20118 / 8
ReadFunctionData
Notes
With the command ReadFunctionData you
can readback DSP functions. You have to
send the ReadFunctionData command and
add the command number from the „SetCommand“ for the specific function as data
byte 1.
This way you can readback all dsp functions.
Data readback example for volume (command 0x87)
Device 1, volume for channel 1
Master send:
1. Byte Startbyte 0xF0
2. Byte Device Adress 0x01
3. Byte Databyte Count 0x01
4. Byte Command Byte 0x0A
5. Byte Channel 0x01
6. Byte Index 0x01
7. Byte Command 0x87
Slave returns (-0.2dB) in this example:
1. Byte <CB> 0xFF // volume
2. Byte Volume_H 0x01 // volume
3. Byte Volume_L 0xFE // volume
4. Byte Flags 0x01 // flags
5. Byte Device Address 0x01
6. Byte Endbyte 0xF0
Loading...