ProSoft Technology PTQ-AFC - Manual (Page 241)

PTQ-AFC ♦ Modicon Quantum Platform Reference
Liquid and Gas Flow Computer for Hydrocarbon Products User Manual
ProSoft Technology, Inc. Page 241 of 259
June 23, 2011
The CTS timeout and both delays are in units of 5ms (200Hz system clock), with
valid values from 0 thru 255, and are significant only for transmission of outgoing
Modbus messages. The receive timeout is in units of 0.1 second, with valid
values from 0 thru 255 (where 0 implies the default of 5, that is, one-half second),
and is significant only for the last port when configured as a Modbus master. The
UART parameters and port options word is a bitmap:
Bit Parameter Value
bits 0 to 2 Baud 000: none; see below
001: 300 baud
010: 600 baud
011: 1200 baud
100: 2400 baud
101: 4800 baud
110: 9600 baud
111: 19200 baud
bits 3 to 4 Parity 00: no parity
01: odd parity
10: even parity
11: no parity (should not be used)
bit 5 Data bits 0: 8 data bits
1: 7 data bits
bit 6 Stop bits 0: 1 stop bit
1: 2 stop bits
bit 7 Modbus mode 0: RTU mode
1: ASCII mode
bit 8 Modbus orientation 0: slave
1: master (permitted only for last port)
bit 9 Primary slave
accessibility (not
meaningful for master
port) 0: primary slave accessible through this port
1: primary slave not accessible (not permitted for Port 1)
bit 10 Swap Modbus bytes
bit 11 Swap Modbus words
bit 12 Disable pass-thru (not meaningful for master port)
bits 13 to 15 [reserved]
A change in configuration takes effect after transmission of the response to the
Modbus command that causes the change; the response is sent using the old
configuration, but subsequent Modbus commands to the reconfigured port must
use the new one. Writing a baud code of 0 means that the current configuration
is not to be changed, and all other items are ignored. Default values are 6 for the
bitmap (9600,N,8,1,RTU,slave,primary,noswap,passthru) and 0 for the timeout
and both delays. The message transmission procedure is:

Raise RTS.
 If TmoC is zero ignore CTS, else wait up to TmoC clock ticks for CTS.
 Delay for Dly1 clock ticks.
 Transmit message.
 Delay for Dly0 clock ticks.
 Drop RTS.