Sterlco M2B+ Controller - Manual (Page 48)

48 of 68
5-18 Serial Communications Operation
The controller communicates with a host machine via an RS232 or RS485 communication link
when the communication option card is installed in the J8 slot on the motherboard. There are
two versions of this option card; one is populated with the ICs to support RS232, and the other
is populated with the ICs to support RS485. All data is sent and received in the bit data format,
using 10 bits: 1 start bit, 8 data bits, no parity bits, and 1 stop bit. This communications
options card uses the J12 connector.
The software supports two protocols, SPI and MODBUS, which are user selectable in the
menus. All communication parameters can be accessed through the setup menus only when a
communication option card is installed:
Primary Menu: “Comm Addr(Hex)=xxxx” specifies the operating address in hex from 0001H
to 03E7H. (This parameter is duplicated in Menu 3.)
Secure Menu: “Comm Protocol = xxx” select either SPI or MODBUS.
Secure Menu: “Comm Addr(Hex)=xxxx” specifies the operating address in hex from 0001H
to 03E7H.
Secure Menu: “Comm Baud Rate=xxxx” select 300, 1200, 2400, 4800, 9600, or 19.2KB.
Secondary Menu: “Comm Local/RMT” [RMT enables serial communication]
Port Address
Operator selection of the address to use is from a menu parameter selection of 1H to 3E7H.
For MODBUS configuration, this address setting must be set between 1
and 247 (0x00Hex to 0xF7Hex).
The default value for this parameter is 1H. The SPI DEVID specified in the SPI Protocol
Specification field is set by this PORT address setting.
For SPI configuration, the address setting must be set between 32 and 255
(x20Hex to 0x0xFFHex).
Baud Rate and Data Format
Operator selection of the baud rate to use is from a menu parameter selection of 300, 1200,
2400, 4800, 9600, or 19.2KB. The default value for this parameter is 9600 Baud. The data
format is 1 start bit, 8 data bits, no parity, and 1 stop bit for all protocols.
Protocols
Onboard protocols are Modicon Modbus RTU and SPI. SPI is only available in RS485. These
follow the standard rules for these protocols. All other desired protocols will require an
external gateway to be supplied by the manufacturer. Operator selection of the protocol to
uses is from a menu parameter selection. The default protocol is MODBUS.
When the protocol is changed, the port address must be set correctly in the
range appropriate for the protocol.