32
keys, scroll to CONFIG ADDRESS SET, then press Enter to confirm., Now the load will display ADDRESS
ADDR= xxx. Enter the new address using numeric keys, and press the Enter key again to confirm.
Note: Only whole numbers from 1 - 200 range will be accepted as valid additional addresses.
3)Selectingthe check mode
Press the Shift+0 keys in sequence, placing you in Main Menu mode. The XT 98XX DC Electronic Load
will now display MENU CONFIG. Press the Enter key to confirm.At CONFIG menu, use the up and down
▲ and ▼ keys, adnd scroll to CONFIG COMM.PARITY, and press Enter. The load will now display
COMM.PAR xxxxxThere are three choices, ODD, EVEN and NONE to select from. Enter the numeric
value for the parity mode using the keypad and press ENTER. Now the load has its parity mode set.
4.8.2 Setup Baudrate
Press the Shift+0 keys in sequence, placing it in Main Menu mode. The XT 98XX DC Electronic Load will
now display MENU CONFIG. Press the Enter key to confirm. At CONFIG menu, use the up and down ▲
and ▼ keys, and scroll to CONFIG BAUDRATE SET, then press Enter to confirm. The load will now
display BUADRATE xxxxx. The DC Load offers you six choices of baud rate to set. Use the use up
and down ▲ and ▼ keys to set the desired communications rate from 2400,9600,14400,28800,57600
and115200 baud.
4.8.3 Data
The M97 series loads operate in the Modbus protocol. Accordingly, in some data frames, the date length
is fixed, but in other data frames, the length is not fixed. According to this protocol, all the hexidecimal data
and the floating point number are fixed in the High Byte and the unfixed data length fields are in the Low
Byte. In addition,the output value of a force single coil must be either 0x0000 or 0xFF00. 0x0000 means
OFF, and 0xFF00 means ON. All other values are invalid and will not affect the coil.
4.8.4 Function Code
Function codes are single byte hex numbers; there are 4 functional modes as below:
Function Code
Description
0x01 Read Coil Status, read the data by each bit
0x05 Force Single Coil, write the data by each bit
0x03 Read Holding Registers, read the data by each word
0x10 Preset Multiple Registers, write the data by each word
4.8.5 Error checking (CRC)
The M97 series loads use the Cyclic Redundancy Check (CRC). The CRC field examines the contents of
the entire message. The CRC fileld is two bytes, containing a 16-bit binary value.When the CRC is
appended to the message, the low-order byte is appended first, followed by the high-order byte.
The discipline is as follows:
a) Set one hex CRC register, and give it the initial value as 0xFFFF.
b) Make bit xor the first byte of the frame date and the lower 8 bit of the CRC register. Save the bit
xor result into the CRC register.
c) Right move the CRC register for 1 byte, and make certain the lowest bit is set as1. Iif the lowest
bit is 1, then make the bit xor for the CRC register and the fixed data as 0xA001.
d) Repeat c) 8 times.
e) Repeat steps b,c andd, for the next byte of frame data until the last byte.
f) The last number of the CRC register is the last parity check result. Place it at the end of the frame
data, keeping the lower 8 bits in the latter and higher 8 bits in former.
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