Bradley Smoker PLC-5 Use this Mode For, Point-to-Point, DF1 Master Mode, DF1 Slave Mode

Communicating with Devices on a Serial Link 10-3

In system mode, you can send data to a device using:

• the message (MSG) instruction; or

• ASCII write instructions (send as an ASCII string)

All data is encapsulated inside a DF1 protocol packet; therefore, the controller can communicate only with peripheral devices that support the DF1 protocol.

Examples of DF1 peripheral devices are:

	• personal computers
	• communication modules such as 1771-KF2 series C, 1771-KE,
	1771-KF, and 1785-KE
	• modems
Use this Mode	For
Point-to-Point	communication between a PLC-5 controller and one other DF1 protocol compatible device
	In point-to-point mode, a PLC-5 controller uses DF1 full-duplex protocol.
DF1 Master Mode	control of polling and message transmission between the master and each remote node
	In master mode, a PLC-5 controller uses DF1 half-duplex polled protocol.
	The master/remote network includes one PLC-5 controller configured as the master node and
	up to 254 remote nodes. You link remote nodes using modems or line drivers.
	A master/remote network can have node numbers from 0 to 376 (octal). Node 377 is reserved
	for broadcast. Each node must have a unique node address. Also, at least 2 nodes must exist
	to define your link as a network (1 master and 1 remote station are two nodes).
DF1 Slave Mode	using controller as a remote station in a master/slave serial communication network
	When there are multiple remote stations on the network, you link remote nodes using
	modems or line drivers. When you have a single remote station on the network, you do not
	need a modem to connect the remote station to the master; you can configure the control
	parameter for no handshaking. You can connect from 2 to 255 nodes to a single link. In slave
	mode, a PLC-5 controller follows DF1 half-duplex protocol.
	One node is designated as the master and it controls who has access to the link. (For
	example, a master can be a PLC-5/250 or PLC-5/40 controller or a computer running
	ControlView SCADA option software. All other nodes are remote stations and must wait for
	permission from the master before transmitting. The master (except PLC-5/250) can send and
	receive messages from all nodes on the link and to nodes on other Data Highway links
	connected to the multidrop; whereas, a remote station can only respond to the master.

Publication 1785-UM012D-EN-P - July 2005