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A sub-miniature DB-9 connector on the rear panel of the EIK CW Power Supply supports half-duplex RS-422 or RS-485 serial communication with an external computer.
Pin Number | RS-422 | RS-485 |
1 | N.C. | N.C. |
2 | * | |
3 | R+ | R+/T+ |
4 | T+ | * |
5 | GND | GND |
6 | T- | * |
7 | RL** | RL** |
8 | * | |
9 | R- | R-/T- |
*For 2-wire RS-485 operation, jumper pins 2 and 4 (R+ to T+) and pins 6 and 8 (R- to T-)
**To terminate the receiver with 120 Ohms, jumper pin 9 (R-) to pin 7 (RL). This termination is not usually needed at 19,200 baud or below.
Serial Communication Configuration
- From the top-level menu, select SETUP in Menu 3. Press MORE until Setup Screen 4 appears.
- Turn the ADJUST knob until square brackets appear around the desired parameter.
- Press S1 (SET) to change to arrows, which will allow changes.
- Turn the ADJUST knob to change values.
- Press S1 (SET) to store the value.
- Data Bits 7 or 8, normally 8
- Stop Bits 1 or 2, normally 1
- Parity odd, even, or none, normally none
- ID between 1 and 99, chose unique equipment number
- Baud Rate choices: 19,200, 9600, 7200, 3600, 2400, 2000, 1800, 1200, 600, 300, 150, or 134.5
Software Command Format
Command blocks are formatted as follows:
STX | > | 0 | 1 | b | R | D | E | K | ETX | 0 | 1 | CR |
Prefix | Address | blank | Command | Suffix | Checksum | Terminator |
All characters are 8-bit ASCII.
The address must match the value in the setup screen.
The checksum is the hexadecimal sum of all ASCII character values following the STX character, up to and including the ETX character; divided by 256d (100h).
Example message exchange:
HOST:
STX | > | 0 | 1 | b | R | D | S | T | A | T | ETX | 0 | 1 | CR |
LOCAL: