How to remotely control Voltage On Set and Voltage Off Set function in 85XX series load?

Applicable Firmware version:  1.84 only

If your DC electronic load has firmware version 1.84, then this documentation will describe how you can control the "VOLTAGE ON SET" and "VOLTAGE OFF SET" features made available in the instrument.  If you have versions below 1.84, this feature is not available.

How to verify firmware version

Power off the electronic load. Press and hold "Shift" key with one hand, while pressing the power on key with the other to power on the instrument. Keep holding the "Shift" key until the display shows: XX V  XX A XX W where XX indicates the maximum voltage, current, and power input rating of the load you have. Turn the rotary knob a few times until the display shows: VER: X.XX .  The X's indicate the version number you have.

Remote Commands for Voltage On Set

The 85XX series remote communication protocols are structured in packets of 26 bytes, as described in the user manual.  To control the Voltage On Set, here are the command structures (all values are in Hex format):

SET Voltage On Set:

• 1st byte: 0xAA
• 2nd byte: Address
• 3rd byte:  0x10
• 4th byte: Lowest byte of Von value
• 5th byte: Lower byte of Von value
• 6th byte: Higher byte of Von value
• 7th byte: Highest byte of Von value
• 8th - 25th byte:  System reserve (should be left as 0x00)
• 26th: Checksum of 1st - 25th byte (Take the least significant digits)

Note: 4th - 7th byte represent voltage value in little endian format in which 1 represents 1 mV.  For example, suppose you want to set the voltage to 16.23V. Since 1 represents 1mV, therefore 16.23V translates to 16,230 in decimal. With 4 bytes in Hex, that would be 0x0003F66. Since the bytes are ordered in little-endian format, 0x66 would be the 4th byte, 0x3F the 5th byte, 0x00 as 6th byte, and 0x00 as the 7th byte.

Then to set Voltage On to 16.23 V, the complete packet frame will be (1st to 26th byte in order): AA 00 10 44 3F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 3D

Read Voltage On Set:

• 1st byte: 0xAA
• 2nd byte: Address
• 3rd byte: 0x11
• 4th byte: 0x00
• 5th byte: 0x00
• 6th byte: 0x00
• 7th byte: 0x00
• 8th - 25th byte:  System reserve (should be left as 0x00)
• 26th: Checksum of 1st - 25th byte (Take the least significant digits)

Note: Upon querying to read the value yet for Voltage On Set, the load will reply with a status packet if the command was sent successfully.  Check user manual for details.

Remote Commands for Voltage Off Set

The 85XX series remote communication protocols are structured in packets of 26 bytes, as described in the user manual. To control the Voltage Off Set, here are the command structures (all values are in Hex format):

SET Voltage Off Set:

• 1st byte: 0xAA
• 2nd byte: Address
• 3rd byte:  0x12
• 4th byte: Lowest byte of Von value
• 5th byte: Lower byte of Von value
• 6th byte: Higher byte of Von value
• 7th byte: Highest byte of Von value
• 8th - 25th byte:  System reserve (should be left as 0x00)
• 26th: Checksum of 1st - 25th byte (Take the least significant digits)

Note: 4th - 7th byte represent voltage value in little endian format in which 1 represents 1 mV.  For example, suppose you want to set the voltage to 16.23V. Since 1 represents 1mV, therefore 16.23V translates to 16,230 in decimal. With 4 bytes in Hex, that would be 0x0003F66.  Since the bytes are ordered in little-endian format, 0x66 would be the 4th byte, 0x3F the 5th byte, 0x00 as 6th byte, and 0x00 as the 7th byte.

Then to set Voltage On to 16.23 V, the complete packet frame will be (1st to 26th byte in order): AA 00 10 44 3F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 3D

Read Voltage Off Set:

• 1st byte: 0xAA
• 2nd byte: Address
• 3rd byte:  0x13
• 4th byte: 0x00
• 5th byte: 0x00
• 6th byte: 0x00
• 7th byte: 0x00
• 8th - 25th byte:  System reserve (should be left as 0x00)
• 26th: Checksum of 1st - 25th byte (Take the least significant digits)

Note: Upon querying to read the value yet for Voltage Off Set, the load will reply with a status packet if the command was sent successfully.  Check user manual for details.