Use Table 2.1 to help you understand the communication parameters you need to specify on the Channel Configuration screen for
standard-communication mode.
Use Worksheet 2.1 (page D-5) for an example configuration and to record your station’s configuration.
Table 2.1 Communication Parameters for a PLC-5 Master Station Using Standard-Communication Mode
RSLogix 5 Tab Parameter Selections
Channel 0 Diagnostic File Select an unused integer file to store channel status information. You must define a diagnostic file in order to be able to view channel 0 status. See See Table 2.2 on page 2-8 for a
description of what is in this file. Remote Mode
Change
Check enable remote mode change if you want to switch the configuration of the channel during runtime. Leave the parameter set at the default (unchecked) if you are not using this feature.
Mode Attention Character
Select a character that will signal a remote mode change. Leave the parameter set at the default if you are not using remote mode change.
System Mode Character
Select a character that will signal the channel to switch into system mode. Leave the parameter set at the default if you are not using remote mode change.
User Mode Character
Select a character that will signal the channel to switch into user mode. Leave the parameter set at the default if you are not using remote mode change.
Serial Port Baud Rate Select a communication rate that all devices in your system support. Configure all devices in the system for the same communication rate.
Bits Per Character Match the number of bits per character to the devices with which you are communicating. Stop Bits Match the number of stop bits to the devices with which you are communicating. Control Line This parameter defines the mode in which the master driver operates. Choose a method
appropriate for your system’s configuration:
• If you are not using a modem, choose NO HANDSHAKING.
• If the master modem is full duplex and the slave modem is full-duplex, choose FULL-DUPLEX MODEM.
• If all the modems in the system are half-duplex, choose HALF-DUPLEX MODEM WITHOUT CONTINUOUS CARRIER.
Serial Port Error Detect With this selection, you choose how the processor checks the accuracy of each DF1 packet transmission.
BCC: This algorithm provides a medium level of data security. It cannot detect:
• transposition of bytes during transmission of a packet
• the insertion or deletion of data values of zero within a packet
CRC: This algorithm provides a higher level of data security.
Select an error detection method that all devices in your system support. When possible, choose CRC.
Options Station Address Define the octal address of the processor on the DF1 half-duplex link. Each station on a link must have a unique address. Choose an address between 0 and 3768.
Station address 3778 is the broadcast address, which you cannot select as a station’s individual address.
DF1 Retries Defines the number of times a master station retries either a message before the master station declares the message undeliverable, or poll packet to an active station before the master station declares that station to now be inactive.
RTS Send Delay RTS send delay is the amount of time, in 20 millisecond increments, that elapses between the assertion of the RTS signal and the beginning of the message transmission. This time allows the modem to prepare to transmit the message.
The Clear to Send (CTS) signal must be high for transmission to occur.
RTS Off Delay RTS off delay is the amount of time, in 20 millisecond increments, that elapses between the end of the message transmission and the de-assertion of the RTS signal. This time delay is a buffer to make sure that the modem has transmitted the message but should normally be left at zero.
ACK Timeout Define the amount of time, in 20 millisecond increments, that you want the processor to wait for an acknowledgment from a slave station to its transmitted message before the processor retries the message or the message errors out.
Reply Message Wait
Define the amount of time, in 20 millisecond increments, that the master station will wait after receiving an ACK (to a master-initiated message) before polling the slave station for a reply.
Choose a time that is, at minimum, equal to the longest time that a slave station needs to format a reply packet. This is typically the maximum scan time of the slave station.
Note: This field is only valid if the polling mode field is configured to be MESSAGE BASED. MSG Application
Timeout
Define the number of 30 second increments within which the reply message must be received before the error bit is set on the message. The timer starts when the ACK is received. Polling Polling Mode If you want to receive:
• only one message from a slave station per its turn, choose STANDARD (SINGLE MESSAGE TRANSFER PER NODE SCAN).
Choose this method only if it is critical to keep the poll list scan time to a minimum.
• as many messages from a slave station as it has, choose STANDARD (MULTIPLE MESSAGE TRANSFER PER NODE SCAN).
Master Message Transmit
If you want the master station to:
• send all of the master station-initiated MSG instructions to the slave stations before polling the next slave station in the poll list, choose Between Station Polls.
This method makes certain that master station-initiated messages are sent in a timely and regular manner (after every slave station poll).
• only send master station-initiated MSG instructions when the master’s station number appears in the polling sequence, choose In Poll Sequence.
With this method, sending master station-initiated messages are dependent upon where and how often the master station appears in the poll list. To achieve the same goal as the Between Station Polls method, the master-station’s address would have to appear after every slave-station’s address.