# Cyrustek ES51922 serial protocol

The information in this document are taken from the [Cyrustek ES51922 datasheet](http://www.cyrustek.com.tw/spec/ES51922.pdf).

## Serial signaling

19230 baud, 7 bits frames, odd parity, 1 stop bit.


## Packet format

14 frames, including the line ending markers CR and LF.


|    0  |      1 |      2 |      3 |      4 |      5 |        6 |      7 |       8 |       9 |      10 |      11 | 12 | 13 |
|-------|--------|--------|--------|--------|--------|----------|--------|---------|---------|---------|---------|----|----|
| Range | Digit4 | Digit3 | Digit2 | Digit1 | Digit0 | Function | Status | Option1 | Option2 | Option3 | Option4 | CR | LF |


## Fields

### Range

| Code      |     V    |   2-range auto A   |   22A  | Manual A |  ADP  |     Ω   | Frequency | Capacitor |
|:---------:|---------:|:-------------------|-------:|---------:|:-----:|--------:|----------:|----------:|
|  011 0000 |  2.2000V | Lower range (IVSL) | 22.000A|  2.2000A |  ADP4 |  220.00Ω|   22.00Hz |  22.000nF |
|  011 0001 |  22.000V | Higher range (IVSH)|        |  22.000A |  ADP3 | 2.2000KΩ|   220.0Hz |  220.00nF |
|  011 0010 |  220.00V |                    |        |  220.00A |  ADP2 | 22.000KΩ|           |  2.2000µF |
|  011 0011 |  2200.0V |                    |        |  2200.0A |  ADP1 | 220.00KΩ| 22.000KHz |  22.000µF |
|  011 0100 | 220.00mV |                    |        |   22000A |  ADP0 | 2.2000MΩ| 220.00KHz |  220.00µF |
|  011 0101 |          |                    |        |          |       | 22.000MΩ| 2.2000MHz |  2.2000mF |
|  011 0110 |          |                    |        |          |       | 220.00MΩ| 22.000MHz |  22.000mF |
|  011 0111 |          |                    |        |          |       |         | 220.00MHz |  220.00mF |


### Digits

|   Code   | Digit |
|:--------:|:-----:|
| 011 0000 |   0   |
| 011 0001 |   1   |
| 011 0010 |   2   |
| 011 0011 |   3   |
| 011 0100 |   4   |
| 011 0101 |   5   |
| 011 0110 |   6   |
| 011 0111 |   7   |
| 011 1000 |   8   |
| 011 1001 |   9   |


### Function

|   Code   |    Mode       |     VBAR=0     |        VBAR=1       |
|:--------:|:--------------|:--------------:|:-------------------:|
| 011 0000 |  22A Current  |   Don't care   |      Don't care     |
| 011 0001 |     Diode     |   Don't care   |      Don't care     |
| 011 0010 |   Frequency   |   Don't care   |      Don't care     |
| 011 0011 |       Ω       |   Don't care   |      Don't care     |
| 011 0100 |  Temperature  |   Don't care   |      Don't care     |
| 011 0101 |  Continuity   |   Don't care   |      Don't care     |
| 011 0110 |  Capacitance  |   Don't care   |      Don't care     |
| 011 0111 |       ?       |        ?       |           ?         |
| 011 1000 |       ?       |        ?       |           ?         |
| 011 1001 |Manual Current |   Don't care   |      Don't care     |
| 011 1010 |       ?       |        ?       |           ?         |
| 011 1011 |     Voltage   |   Don't care   |      Don't care     |
| 011 1100 |       ?       |        ?       |           ?         |
| 011 1101 |Auto µA Current|Auto µA Current |Auto 220.00A/2200.0A |
| 011 1110 |      ADP      |   Don't care   |      Don't care     |
| 011 1111 |Auto mA Current|Auto mA Current |Auto 22.000A/220.00A |


### Status

| Bit 6 | Bit 5 | Bit 4 | Bit 3 | Bit 2 | Bit 1 | Bit 0 |
|:-----:|:-----:|:-----:|:-----:|:-----:|:-----:|:-----:|
|   0   |   1   |   1   | Judge | Sign  | BATT  |   OL  |


### Options

#### Option 1

| Bit 6 | Bit 5 | Bit 4 | Bit 3 | Bit 2 | Bit 1 | Bit 0 |
|:-----:|:-----:|:-----:|:-----:|:-----:|:-----:|:-----:|
|   0   |   1   |   1   |  MAX  |  MIN  |  REL  |  RMR  |

#### Option 2

| Bit 6 | Bit 5 | Bit 4 | Bit 3 | Bit 2 | Bit 1 | Bit 0 |
|:-----:|:-----:|:-----:|:-----:|:-----:|:-----:|:-----:|
|   0   |   1   |   1   |  UL   | Pmax  | Pmin  |   0   |

#### Option 3

| Bit 6 | Bit 5 | Bit 4 | Bit 3 | Bit 2 | Bit 1 | Bit 0 |
|:-----:|:-----:|:-----:|:-----:|:-----:|:-----:|:-----:|
|   0   |   1   |   1   |  DC   |  AC   | AUTO  | VAHZ  |

#### Option 4

| Bit 6 | Bit 5 | Bit 4 | Bit 3 | Bit 2 | Bit 1 | Bit 0 |
|:-----:|:-----:|:-----:|:-----:|:-----:|:-----:|:-----:|
|   0   |   1   |   1   |   0   | VBAR  | Hold  |  LPF  |