/******************************************************************************
*
* Serial Protocol
*
* The first two bytes are the device address in ascii decimal, 1 to 99, with 99
* addressing all boards, which is only valid for setting min and max voltage.
*
* commands can be abreviated by typing to the unique character, and ending
* with a period '.'.
* 01voltage Unit 1 voltage query: returns voltage in ascii
* 02v. Unit 2 voltage query: returns voltage in ascii
* 03sethigh 15.55 Set Unit 03 regulation voltage to 15.55V
* 99seth. 14.50 Set all units regulation voltage to 14.50V
* 04setlow 10.00 Set Unit 4 undervoltage warning level to 10.00V
* 05minvolts Read unit 5 minimum voltage recorded
* 06maxvolts Read unit 6 maximum voltage recorded
* 07hstclear Clear unit 7 recorded min and max voltages
* 99h. Clear all units min and max history
* 08status Read status of unit 08. Returns a hexadecimal value as the
* sum of:
* Disabled 0x80
* Shunting 0x40
* Under Voltage 0x20
* Over Voltage 0x10
* Has Been Low 0x08
* Over Temp 0x04
* Normal Oper. 0x00
* 09eepromwr xxx yy Write value 'yy' to eeprom location 'xxx' on unit 9
* 10gethighv Read regulation voltage on unit 10
* 11readlowv Read low voltage warning limit on unit 11
* 13temperat Read unit temperature
* 12xtrntemp Read external temperature on unit 12
* 14disable Disable Shunt on board 14
* 15enable Enable shunt on board 15 
*
******************************************************************************/