Honeywell VC4 User Manual page 133

The VC4™ monitor supports multiple baud rates. These user selectable rates are 1200, 2400,
4800, 9600, and 19,200. Additional port settings are 8-bit, 1 stop bit, and no parity.
The slave is identified by an address programmed into the VC4™ monitor (selectable 1-255). If
more than one VC4™ monitor is used, each must have a unique address.
The equipment (master) is always at address 0. Each VC4™ monitor will respond to a signal
directed to it from the equipment. To prevent a collision of messages, the master must avoid
transmitting any information after a packet until the slave responds. Typically this occurs within
1000 milliseconds.
Communication Port
Access to the VC4™ protocol is through the COM port. This port is a DB-9 female connector.
This port is designed for bidirectional communications between the VC4™ instrument and your
equipment.
Signals present at the port conform to RS-232, RS-422, or RS-485 specifications. Again, this is
based on which interface option was installed in your VC4™ instrument. The pin-out
specifications for each option are as follows:
VC4™
RS-232 (Part Number 874270)
Pin Number
2
3
5
RS-422 (Part Number 874326)
Pin Number
2
3
4
5
RS-485 (Part Number 874556)
Pin Number
2
3
7
B (Transmit/Receive +)
A (Transmit/Receive -)
133
Signal
Transit
Receive
Ground
Signal
Receive +
Receive -
Transmit -
Transmit +
Signal
Signal Ground
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