12.4.8
Write Port Control Function (4304)
This function forces RTS for the specified port:
12.4.8.1
Example Command Block for the Write Port Control
Function
VALUE
(decimal)
VALUE
(hexadecimal)
MEANING
address
0002
0002
Data block length
a1
0000
0000
NOWAIT mode
a2
0008
0008
Status word memory type (%R)
a3
0000
0000
Status word address minus 1 (%
R0001)
a4
0000
0000
Not used
a5
0000
0000
Not used
a6
4304
10D0
Write port control command
a7
xxxx
xxxx
Port control word
12.4.8.2
Port Control Word
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RTS
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
The Port Control Word can be:
15 RTS Commanded state of the RTS output
1 = Activates RTS
0 = Deactivates RTS
0-14 U Unused (should be zero)
12.4.8.3
Operating Note
For CPU port 2 (RS-485), the RTS signal is also controlled by the transmit driver.
Therefore, control of RTS is dependent on the current state of the transmit driver. If the
transmit driver is not enabled, asserting RTS with the Write Port Control COMMREQ
will not cause RTS to be asserted on the serial line. The state of the transmit driver is
controlled by the protocol and is dependent on the current Duplex Mode of the port. For
2-wire and 4-wire Duplex Mode, the transmit driver is only enabled during transmitting.
Therefore, RTS on the serial line will only be seen active on port 2 (configured for 2-wire
or 4-wire Duplex Mode) when data is being transmitted. For point-to-point Duplex Mode,
the transmit driver is always enabled. Therefore, in point-to-point Duplex Mode, RTS on
the serial line will always reflect what is chosen with the Write Port Control COMMREQ.
242
GFK-1503E
VersaMax PLC User Manual
For public disclosure
Summary of Contents for VersaMax PLC
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