Shihlin electric SDP Series, Manual

Page: 418 / 555

405
9.3 Modbus communication protocol
To communicate with the computer, each servo drive must set its device number(PC20) firstly,
and then the computer controls the individual servo drives according to the device number. The
communication method is MODBUS Networks, and there are two mode of MODBUS network
communication: ASCII (American Standard Code for Information Interchange) and RTU
(Remote Terminal Unit). You can set the communication mode(ASCII or RTU) by PC21
according to your requirements.
Note: USB and MODBUS cannot be used at the same time.
The Shihlin servo drive provides these function codes: 0x03, 0x04, 0x06, 0x10, which
can do relevant communication control with the host controller.
9.3.1 ASCII mode
(a)Code description
Every 8-bit data frame consists of two ASCII characters. For example, if 1 byte of data 75H
(hexadecimal notation) is represented by ASCII "75", which contains the ASCII code of '7' (37H)
and the ASCII code of '5' (35H).
(b)Frame structure
11 bit frame structure(for 8-bit data length)