Nor-Cal SDC15 Controller - Manual (Page 175)

Chapter 8. MODBUS COMMUNICATIONS FUNCTIONS
8 - 1 Outline of Communications
8-1
If the optional model number is provided with the RS-485 communications function, communications with a PC,
PLC or other host devices are available using a user-prepared program.
The communications protocol can be selected from the CPL communications (Controller Peripheral Link:
Yamatake's host communications protocol) and the MODBUS communications. This chapter describes the
MODBUS communications.
■ Features
The features of the SDC15's communications functions are as follows:
• Up to 31 SDC15 units can be connected to a single master station as a host
device.
• When the communications specifications of the host device conform to the RS-
232C interface, the communications converter CMC10L (sold separately) is
required.
The CMC10L allows you to perform the conversion between RS-232C and RS-
485.
• Almost all of the parameters held by the device can be communicated.
For details on communications parameters,
refer to Chapter 9, LIST OF COMMUNICATION DATA .
■ Setup
The following setups are required for performing the MODBUS communications:
• If the optional model number is provided with the RS-485 communications
function, display and setup are available.
• If the communications type is set to MODBUS RTU format, data format (data
length) cannot be displayed nor set up, and the action is fixed to 8-bit data.
Handling Precautions
• Setups can be performed through key operation on the console or the
smart loader package SLP-C35. However, they cannot be performed
via RS-485 communications.
• If you use the Yamatake CMC10L as an RS-232C/RS-485 converter,
set the response time-out (C70) to 3 ms or longer.
Item Display Contents Initial User
(Setting display/bank) value level
CPL/MODBUS 0: CPL 0 Simple,
(Setup setting/Setup bank) 1: MODBUS ASCII format Standard,
2: MODBUS RTU format High
Station address 0: Does not communicate 0
function
(Same as above) 1 to 127
Transmission speed 0: 4800bps 2
(Same as above) 1: 9600bps
2: 19200bps
3: 38400bps
Data format (Data length) 0: 7-bit 1
(Same as above) 1: 8-bit
Data format (Parity) 0: Even parity 0
(Same as above) 1: Odd parity
2: No parity
Data format (Stop bit) 0: 1 stop bit 0
(Same as above) 1: 2 stop bits
Response time-out 1 to 250 ms 3 High
function