Table of Contents
Advertisement
Instruction Manual
8
RS485 serial communications
Two distinctly different RS485 serial communications protocols are available with the IGM402. The first, referred to
as 'BINARY' protocol uses a cyclic redundancy check (CRC) of 8 bits (CRC8) which is similar to the automotive industry
standard J1850 requirements. Sections 8.1 and 8.2 of this user manual apply only to the 'BINARY' protocol version.
The second is the ASCII protocol. Refer to Section 8.3 and
when communicating with the IGM402 over the EIA485 interface.
'BINARY' protocol is the device default setting however we recommend using the ASCII protocol whenever possible.
The BINARY protocol is uncommon, difficult to use and not compatible with readily available PLCs.
Device Specific Serial Communication Info - BINARY Protocol with CRC8
8.1
The standard IGM402 model provides RS485 serial communications. The following information and the RS485
command protocol summary listed in
1. Default settings are 19,200 baud rate, 8 data bits, No Parity, 1 stop bit [Factory default; 19,200, 8, N, 1].
2. The baud rate can be set to various values using the front panel selection keys. See SET COMMS BAUD RATE
in
8.2
table for baud rates available. Baud rate used by device (slave) must be the same as used
section
by the host (master).
3.
Minimum interval between commands sent out over the RS485 bus is 50 msec.
4. 'xx' is the address of the device (00 thru FF).
5. <CR> represents a carriage return, a non-printable character. Do not enter <CR> from your keyboard. A
carriage return, non-printable character may be entered as the Unicode C0 controls specified value: 0D
hexadecimal (13 decimal). From your keyboard, a key entry sequence of CNTL M may be used to obtain the
required character for a carriage return when using certain terminal emulator programs.
6. '_' represents a space. Do not enter '_' (an underscore character) from your keyboard. Instead, press the
space bar on your keyboard.
7. All commands sent to the module start with a '!' character (21 hex), and all normal responses from the
module start with a '*' character (2A hex). Error responses start with a '?'.
8. A valid address must be used [Factory default = 1]. The IGM402 will not respond to a command with an
invalid address.
9. RS485 Command Protocol Summary:
The command protocol for the IGM402 has the following format:
Command: <!><addr><cmd><data><CRC>
Response: <*><addr><cmd><data><CRC>
InstruTech
8.4
for the 'ASCII' protocol version also available for use
section 8.2
can be used to establish serial communications with the IGM402.
IGM402 Hornet
Page 57
Advertisement
Table of Contents
Troubleshooting
