Apex Digital 5708009-C Profibus Termination, Profibus Baud Rate, Profibus Master Reset Command

Apex 1 to 5.5 kW Generator

Placing a switch in the “up” position (toward the number) is the same as indicating

“1” binary. The following example demonstrates switch settings for an address of 12: 0000 1100 = 0x0Ch = 12.

Note: You cannot change the unit’s address from the Profibus master.

Profibus Termination

Please ensure that you follow proper termination procedures if your Apex is the last slave on the Profibus cable. The termination resistors should be on the connector housing of the Profibus cable (not included).

Profibus Baud Rate

The auto-baud feature of AE’s certified Profibus interface adjusts automatically to the rate of the Profibus master system. Baud rates are available in discrete steps from 9600 bits (9.6 kbits) to 12 Mbits. The auto-baud feature operates much like a modem or FAX machine in that, at startup, there is a small delay while the interface “traverses” the different baud rates and then locks in. Please ensure that your Profibus master allows for this delay.

Profibus Master Reset Command

Send the master reset command, Command 119, when the Apex supply has experienced a non-recoverable (“explicit clear”) fault (that is, a configuration fault or a Profibus error fault). We recommend sending this command upon the startup of Profibus communications so that any existing fault indications will be cleared.

Profibus Watch Dog Timer

As a safety feature, the Profibus maintains a watch dog timer that shuts off the Apex supply’s output if the Profibus master stops communicating. The watch dog timer maintains a value for time (between 10 ms and 10 minutes) that the Apex supply waits between commands from the master. The timer counts down this time in 10 ms increments.

If your Profibus system does not calculate the watch dog timer value for you or if you want to modify the existing watch dog timer value, then you may enter a timer value by using the Profibus Set_Prm function call (see DIN 19245 Profibus Standard Part III). To get the actual wait time value, the Apex microprocessor uses the numbers you enter to octet 2 and 3 of the Set_Prm, multiplies them together, and then multiplies the result by 10 ms. Therefore, when using the Set_Prm function call, calculate the numbers for octet 2 and 3 accordingly. Remember, the values for octet 2 and 3 must not be equal to each other or be zero.

Note: You can disable the watch dog timer through the Profibus master.

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