Protocol
Article Authors Note : Little information is available regarding this protocol, so the below data is unverified and provided 'as is'.
Electrical Parameters
| Parameter | Abr. | Transmitting | Receiving | ||||
| Max | Min | Nominal | Max | Min | Nominal | ||
| Transmitting Impedance1 | Ro | 10 Ω | - | - | - | - | - |
| Receiving Impedance | Ri | - | - | - | - | 90 kΩ | 100 kΩ |
| Termination per dimmer2 | Rt | - | - | - | 30 kΩ | 20 kΩ | 24 kΩ |
| Termination capacitor3 | Ct | - | - | - | +25% | -25% | |
| Sync Level | Vs | -6.0 V | -4.0 V | -5.0 V | - | - | - |
| Sync Detector Threshold | Vst | - | - | - | -3.0 V | -2.0 V | -2.5 V |
| Full Level4 | Vf | 5.1 V | 4.9 V | 5.0 V | 5.1 V | 4.9 V | 5.0 V |
| Off Level | Vo | 0.1 V | 0.1 V | 0.0 V | 0.1 V | 0.1 V | 0.0 V |
| Safe Input Levels | Vm | - | - | - | - | +/-10 V | - |
1) Outputs to be short-circuit proof to 0 V to unlimited periods.
2) The termination resistor is paralleled for multiple dimmers received, e.g. 24 dimmers use 1 kΩ.
3) The termination capacitor is set to give a 1 µs time-constant, e.g. for Rt = 1k, Ct = 1,000 pF.
4) Full Level may be adjusted at the control system.
Temporal Parameters
| Parameter | Abr. | Transmitting | Receiving | ||||
| Max | Min | Nominal | Max | Min | Nominal | ||
| End of Frame pulse | Te | 0.5 s | 35 µs | - | 0.5 s | 30 µs | - |
| Inter-Frame period | Ti | 15 µs | 0.5 s | - | - | 10 µs | - |
| Sync Pulse | Ts | 10 µs | 6 µs | 8 µs | 15 µs | 3 µs | - |
| Analogue Valid Delay | Tv | 15 µs | - | - | 20 µs | - | - |
| Analogue Hold period | Th | Td | 50 µs | - | Td | 45 µs | - |
| Total Dimmer period | Td | 0.5 s | 70 µs | - | 0.5 s | 70 µs | - |
| Total Cycle period | Tc | 0.5 s | - | 40 ms | 0.5 s | - | 40 ms |
| Analogue Gate Delay | Tg | 20 µs | 0 | - | - | - | - |
| Number of Dimmers | N | 384 | 1 | - | 768 | 1 | - |
| Slew Rate | - | - | 2 V/µs | 2.5 V/µs | - | 0 | - |
Practical remarks (Found while working on a project to interface DMX512 console to Strand EC90 dimmer):
1) The frame starts with a 0 volt for (> 50us i.e. a channel time) followed by a sync pulse then (channel 1) value and so on tell the whole (384 channels) i.e. you send a 0 valued channel then the 384 channel values, this first 0 valued channel acts as a start code.
2) Every thing works fine when the sync pulse >= 10 us.
3) Unlike DMX512 you cannot shorten the frame to the no. of channels you use, the whole 384 channels + the start 0 valued channel must be sent.
Again these remarks are gained from a practical project with Strand EC90 dimmer.
Read more about this topic: D54 (protocol)