Elpro Technologies 905U-D User Manual download pdf (Page 38)

905U-D Radio Modem User Manual

Man_905D_1.10.doc Page 38

4.4.3 Other Parameters

Radio Data Rate

Select the radio data rate which you want to use. Note that modules will only communicate with

each other if they have the same radio data rate. If you select a rate which is faster than the serial

rate, the 905U-D will automatically set transmission delay parameters in registers S18 and S19

(refer section 3.8). To disable this, deselect the “PLC Mode” box in the Serial configuration

window.

CRC Error Checking

It is normal for error checking to be disabled for transparent mode and enabled for controlled.

However you can select either for either mode. Refer to section 3 of this manual for a

description on the operation of error-checking.

Packet Size (bytes)

This selects the maximum number of bytes which will be transmitted in one message. If more

than this number of bytes is input into the 905U-D, then the module will transmit more than one

message.

The default value is 530 bytes which is the largest packet value. If you are operating in a noisy

radio environment, then the system may be more reliable if you reduce the maximum packet

size and transmit a larger number of small messages rather than a lesser number of large

messages.

Transmit and Receive Hold-off delay times

A “transmit delay” time and a “receive delay” time can be configured. These parameters may be

used to fine tune and give priority to different 905U-D units in a system.

• After each message is transmitted, a 905U-D unit will not transmit another message during the

transmit delay time. This could be used to allow a reply message to be received before the next

message is sent.

• After a message is received, a message will not be transmitted during the receive delay time.

This could be used to delay a reply message until other

messages have been sent.

Serial Port settings

The serial port settings should be selected to match the host

device. Different port settings may be selected for different

modules in the same system.

Serial data rate can be selected between 1200 and 115,200

baud. If you select a rate which is slower than the radio rate,

the 905U-D will automatically set transmission delay

parameters in registers S18 and S19 (refer section 3.8).

To disable this feature, deselect the “PLC Mode” box. Then

there will be no delay - data bytes will be transmitted as

soon as they appear in the input buffer.

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Elpro Technologies 905U-D User Manual Page 38