User manual

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modbus register 40002. Use “0x01, 0x2C” for modbus register

40300.

2. The third and forth bytes specifies the number of registers to read.

Larger requests will generator a modbus error. For example use

‘0x00, 0x14” to read 20 registers.

0x06 – Write Single Register

Note: There are only two addresses that support the 0x06 command:

40098 and 40130.

The Data field contains 4 bytes:

1. The first two bytes specifies the starting register to write to (value =

modbus register - 40000).

2. The second two bytes specifies the 16bit value to write.

CRC

This is the Modbus checksum. Refer to the Modbus standard for

implementation.

Important Details

The message is transmitted in a continuous stream with the LSB of each byte of

data transmitted first. Transmission of each 8-bit data byte occurs with 1 start bit

and 1 stop bit. Parity checking is set to none. The GSC400 supported baud

rates are 9600, 19200, 38400, and 57600.

The recommended request rate is 1000ms but at least ensure there is a delay

between receiving a reply and sending a request of 50ms as the GSC400 needs

time to perform other tasks.

The GSC400 updates holding register addresses from 40050 to 40244 every 1

second. All other modbus registers are updated every 250ms.

For firmware versions below 2.00 the GSC400 power must be cycled off and on

for menu changes to take effect.

Firmware versions 1.38 to 1.46 support 1P

generation Modbus registers.

Firmware versions 2.00 and above supports both 1P

generation as well as 2P

generation registers. For new applications it is recommended to utilize 2P

generation modbus registers.

1. Registers 40086, 40173 and 40174 are supported by firmware versions 2.03

and above.

2. Registers 40146 to 40149 are supported by firmware version 2.07 and above.